Fluid servicing apparatus with integrated manifold and pump assembly

ABSTRACT

A fluid servicing apparatus including a manifold body with a fluid transfer circuit defining a plurality of pathways between a number of ports including first and second pump ports opening into a pump cavity for receiving a pump body coupled to a motor for driving the pump body to circulate fluid in the cavity and through the fluid transfer circuit to exchange fluid between the new and used fluid tanks and a vehicle subsystem fluid reservoir.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation-in-part of co-pending U.S.Ser. No. 10/280,260, entitled Automotive Fluid Servicing Apparatus,filed on Oct. 25, 2002, which is in turn a continuation-in-part ofprovisional application No. 60/350,157, entitled Remotely OperatedVehicle Fluid Exchange System, filed on Oct. 29, 2001, both of which arehereby incorporated by reference in their entireties.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to the field of vehiclemaintenance, and more specifically, to performing fluid exchanges withvehicular subsystem components having fluid reservoirs such as automatictransmission fluid and power steering fluid systems.

[0004] 2. Description of Related Art

[0005] Automatic transmissions and other vehicular fluid systemcomponents frequently require servicing such as replacing used fluidwith fresh fluid in order to properly maintain them and extend the lifeof the component and associated vehicle. Early attempts at developingautomatic transmission fluid transfer machines often resulted inrelatively lengthy and complicated procedures. Many of these devicesrelied upon compressed gases to circulate the fluid and thus requiredsome sort of compressed air source adding to the device's complexity.Such early attempts also required significant manual operation andsupervision as the operator had to continually monitor gauges and otherinstruments to monitor the fluid flow to achieve the desiredperformance.

[0006] While some of these devices proved satisfactory for their time,the next level of automatic transmission fluid transfer machinesintroduced a degree of automation to the fluid exchange process thusreducing the extent of operator intervention. However, the plumbingproposed in an effort to automate the process and perform the stepstypically associated with a complete automatic transmission fluidservice, typically employed a relatively large number of plumbingcomponents such as multiple dedicated pumps, gauges, and several valves.While many of these devices have also proven satisfactory in theirperformance there remains a push for reducing the number of components,costs associated with manufacture and maintenance, and reducing theoverall assembly time while maintaining the capability to perform thedesired procedures.

[0007] Efforts to resolve this long standing problem led to theintroduction of a number of devices of the single pump variety. Someexamples of these single pump devices can be found in U.S. Pat. Nos.5,482,062 and 5,337,708 to Chen; U.S. Pat. No. 5,447,184 to Betancourt;U.S. Pat. No. 5,472,064 to Viken; U.S. Pat. No. 6,035,903 to Few, ownedby assignee of this application; and Japanese Unexamined PatentApplication No. 2-72299. It is clear from a review of the devices shownin these patents that, while success was achieved in reducing somenumber of components, such as the pumps, it was necessary to increasethe remaining plumbing in order to perform the necessary fluid transferprocesses such as complete fluid exchange, recirculation, and drainingboth used and new fluid tanks or such desired processes could notperformed using a single pump. Frequently a separate drain pump or amore complicated and costly reversible pump has been incorporated toperform the desired fluid servicing tasks. While some of these devices,such as that described in U.S. Pat. No. 6,035,903, have provensatisfactory in the field, there remains the ever present need todevelop a fluid changing apparatus with a minimal number of componentsto reduce costs, maintenance, and assembly time, yet still perform thefluid servicing procedures associated with an automatic transmissionservice.

[0008] What is needed is a fluid exchanging apparatus configured toconveniently address the needs of the fluid change operator, such asfaster pump speeds and reduced maintenance time, particularly through areduction in the number of overall couplings and associated hose lengthrequirements, using a single pump configuration integrated into arelatively minimal component fluid transfer system.

SUMMARY OF THE INVENTION

[0009] In accordance with the present invention, an apparatus forperforming fluid exchange servicing functions for a vehicle having afluid reservoir is described herein and more particularly for servicingthe transmission and power steering components of a vehicle system. Suchfluid servicing apparatus generally includes a manifold defining anumber of service ports and a fluid transfer circuit defining aplurality of pathways for transporting fluid therebetween wherein selectports may be coupled to new and used fluid tanks and other select portsmay be coupled to an inlet and outlet of the fluid reservoir to beserviced. The manifold body includes a pump cavity for housing a pumpbody directly coupled to a pump motor. The pump cavity includes firstand second pump ports integrated into the fluid transfer circuit. Afluid flow rate control device is interposed in the fluid transfercircuit and is selectively operable to place each of the ports incommunication with at least one other of the ports. The pump motor andfluid flow rate control device are selectively operable to circulatefluid through the fluid transfer circuit and routing fluid between theports to perform a variety of fluid related servicing procedures.

[0010] In one particular embodiment, the pump cavity is defined withinan extension to the manifold body and the pump body is a vane pump thatis engageable with the drive shaft of the pump motor.

[0011] One aspect of the present invention is the incorporation of firstand second valves acting in tandem to direct fluid through the fluidtransfer circuit and between the ports.

[0012] In another embodiment of the present invention, a proportionalsolenoid valve is interposed in the fluid transfer circuit toselectively adjust the rate of fluid flow passing therethrough.

[0013] Another embodiment of the present invention includes a manifoldwith an auxiliary power steering fluid drain pathway and a reversiblepump motor for draining used power steering fluid from a power steeringreservoir.

[0014] Another feature of the present invention is the incorporation ofa processor receiving fluid level feedback signals from first and secondsensors in communication with the new and used fluid tank. The processoris programmed to automatically perform the fluid exchanging processbased on at least one of the feedback signals by selectively operatingeither the motor or the fluid flow rate control device or a combinationof both.

[0015] Other features and aspects of the present invention will becomeapparent with further reference to the following drawings andspecification.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is a right front perspective view of a preferred embodimentof the automotive fluid servicing apparatus of the present invention;

[0017]FIG. 2 illustrates an exemplary control panel, in enlarged scale,included in the automotive fluid servicing apparatus shown in FIG. 1;

[0018]FIG. 3 is a left rear perspective view, in enlarged scale, of anexemplary manifold incorporated in the automotive fluid servicingapparatus shown in FIG. 1;

[0019]FIG. 4 is a schematic of an exemplary plumbing circuit forwithdrawing used fluid from a power steering reservoir of a vehicle inan alternative embodiment of the automotive fluid servicing apparatus ofthe present invention;

[0020]FIG. 5 is a schematic of an exemplary plumbing circuit for addingnew fluid to a power steering reservoir of a vehicle in an alternativeembodiment of the automotive fluid servicing apparatus of the presentinvention;

[0021]FIG. 6 is a schematic of an exemplary plumbing circuit forperforming servicing procedures in accordance with a preferredembodiment of the automotive fluid servicing apparatus shown in FIG. 1;

[0022]FIG. 7 is a schematic of an alternative plumbing circuit forperforming servicing procedures in accordance with an alternativeembodiment of the automotive fluid servicing apparatus of the presentinvention;

[0023]FIG. 8 is a partial sectional view taken from the plumbing circuitin FIG. 6 illustrating an exemplary recirculation/bypass fluid path;

[0024]FIG. 9 is a partial sectional view taken from the plumbing circuitin FIG. 6 illustrating an exemplary dump fluid path;

[0025]FIG. 10 is a partial sectional view taken from the plumbingcircuit in FIG. 6 illustrating an exemplary drain fluid path;

[0026]FIG. 11 is a partial sectional view taken from the plumbingcircuit in FIG. 6 illustrating an exemplary supply fluid path;

[0027]FIG. 12 is a perspective exploded view, in enlarged scale, of themanifold illustrated in FIG. 3;

[0028]FIG. 13 is a partial sectional view taken from FIG. 7 illustratinga plumbing segment for accommodating a reverse hose flow configuration;

[0029]FIG. 14 is a partial sectional view taken from FIG. 7 illustratinganother plumbing segment for accommodating a reverse hose flowconfiguration;

[0030]FIG. 15 is a partial sectional view taken from the plumbingcircuit in FIG. 6 including an auxiliary valving component in a firstposition illustrating an exemplary fluid distribution path; and

[0031]FIG. 16 is a similar view as illustrated in FIG. 15 including theauxiliary valving component in a second position illustrating analternative exemplary fluid distribution path;

[0032]FIG. 17 is a left rear perspective view, in enlarged scale, of analternative manifold assembly to that shown in FIG. 3;

[0033]FIG. 18 is a rear view of the manifold assembly, in enlargedscale, of the manifold assembly of FIG. 17;

[0034]FIG. 19 is a top view of the manifold assembly, in enlarged scale,of the manifold assembly of FIG. 17;

[0035]FIG. 20 is a front view of the manifold assembly, in enlargedscale, of the manifold assembly of FIG. 17;

[0036]FIG. 21 is a left hand end view of the manifold assembly, inenlarged scale, of the manifold assembly of FIG. 17;

[0037]FIG. 22 is a right hand end view of the manifold assembly, inenlarged scale, of the manifold assembly of FIG. 17;

[0038]FIG. 23 is a bottom view of the manifold assembly, in enlargedscale, of the manifold assembly of FIG. 17;

[0039]FIG. 24 is a perspective exploded view, in enlarged scale, of themanifold of FIG. 17;

[0040]FIG. 25 is a schematic of an alternative plumbing circuit forperforming servicing procedures in accordance with an alternativeembodiment of the automotive fluid servicing apparatus of the presentinvention;

[0041]FIG. 26 is a partial sectional view taken from the plumbingcircuit in FIG. 25 illustrating an exemplary drain fluid path;

[0042]FIG. 27 is a partial sectional view taken from the plumbingcircuit in FIG. 25 illustrating an exemplary supply fluid path;

[0043]FIG. 28 is a partial sectional view taken from the plumbingcircuit in FIG. 25 illustrating an exemplary recirculation/bypass fluidpath;

[0044]FIG. 29 is a partial sectional view taken from the plumbingcircuit in FIG. 25 illustrating an exemplary dump fluid path;

[0045]FIG. 30 is a sectional view taken from the plumbing circuit inFIG. 25 illustrating an exemplary power steering fluid drain path;

[0046]FIG. 31 is a partially exploded rear view, in enlarged scale, ofthe manifold assembly of FIG. 17;

[0047]FIG. 32 is a rear perspective view, in enlarged scale, of analternative embodiment of a fluid servicing apparatus according to thepresent invention with the outer housing removed exposing the fluidtanks;

[0048]FIG. 33 is a fragmented, sectional view, in enlarged scale, takenalong lines 33-33 of FIG. 32;

[0049]FIG. 34 is a sectional view, in enlarged scale, taken along lines34-34 of FIG. 32;

[0050]FIG. 35 is a close up view taken from the oval 35 in FIG. 32; and

[0051]FIG. 36 is a block diagram of the control system incorporated inthe embodiment illustrated in FIG. 32.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0052] Referring now to FIGS. 1, 3 and 6, an exemplary embodiment of anautomotive fluid servicing apparatus, generally designated 20, of thepresent invention is illustrated. In general, such fluid servicingapparatus is incorporated in a convenient, portable wheeled cabinet 22housing a plumbing subsystem and an electrical command subsystemcooperating to drain fluid from a serviceable component, add fluid tothe serviceable component, circulate fluid between the serviceablecomponent and the apparatus, and drain collected or other stored fluidusing a single, common pump 24 and an integrated manifold assembly 26 asdirected by a service technician and controlled by aprocessor/controller 28.

[0053] Plumbing Subsystem

[0054] Turning to FIGS. 3, 6, and 12, at the heart of the plumbingsubsystem is the integrated manifold assembly 26 housing a fluid circuit30 formed in a rectangular manifold body 31 having a top side 33,opposing bottom side 35, rear side 37, front side 43, and two opposingends 45, 47. The body sides and ends have generally planar surfacescooperating to form a rectangular block measuring about six inches wideby three inches deep by three inches high and defining a number ofmanifold ports for connecting to various conduits and other hydrauliccomponents. In this exemplary embodiment, there are six conduit ports.

[0055] With particular reference to FIG. 12, an exhaust port 32, areturn port 34, a drain port 36, and a fresh fluid supply port 38 openoutwardly on the rear side 37 of the manifold body 31. While each ofthese ports are shown on the same side of the manifold body in FIG. 12,it will be appreciated that the ports may be placed at other suitablelocations on the manifold body. For instance, these same manifold portsare shown on different sides of the manifold body 31 in FIG. 6 for easeof description and clarity and may also provide suitable port locationsand is not meant to be limiting in any manner. Other suitable locationswill occur to one of ordinary skill in the art. Each manifold port isthreaded for coupling with one end of a respective conduit, hose, orother suitable tubing or piping, which are in turn connected to adesired source or destination. For ease of assembly, it is preferable tothread one portion of each hose coupling into the respective threadedport opening. The threaded coupling component is constructed to allowthe assembler to merely press the free end of the selected conduit intothe complementary coupling component threaded into the port. Suitablecouplings of this type are available from Parker Hannifin under theTrueSeal trade name.

[0056] More specifically, with reference to FIGS. 3, 6, and 12, a usedfluid conduit 39 connects between the drain port 36 and a used fluidcollection tank 40 to carry fluid therebetween. Similarly, the freshfluid supply port 38 connects via a new fluid supply conduit 41 to a newfluid tank 42. Such used fluid collection tank 40 is constructed to holda sufficient amount of used fluid to accommodate at least complete drainprocedure and preferably more. The new fluid tank 42 is typicallyconstructed to hold a sufficient volume of fresh fluid to accommodate asingle fill procedure and preferably has a greater capacity as well.This fresh fluid source 42 may be filled through a fill hole (notshown). As it is preferred that the servicing apparatus maintain aportable capability, the used and new fluid tanks are preferably mountedinside the cabinet 22 (FIG. 1) which is sized to accommodate thepreferred tank capacities. It has been found that a 24 quart capacityfor both the new and used fluid tanks accommodates most servicingprocedures.

[0057] With continued reference to FIGS. 3, 6, and 12, furtherconvenience is provided by a set of servicing hoses, 44 and 46respectively for connecting between the return port 34 and the exhaustport 32 of the servicing apparatus 20 and the influent line and effluentline of the serviceable component such as an automatic transmission asis well known to one of ordinary skill. The use of conventional adaptersis also contemplated if necessary. The connectors illustrated in FIG. 3are exemplary and not meant to be limiting in any manner as othersuitable connectors will occur to one of ordinary skill. Such connectionplaces the transmission in fluid communication with the servicingapparatus 20 as will be discussed below. The manifold body 31 furtherincludes a suction port 50 and a pressure port 52 located on the topside 53 of the manifold body (FIG. 12). These ports are also threadedfor receiving one part of corresponding suction and pressure hosecouplings 54, 56, which are connected at their opposite ends to therespective suction (inlet) and pressure (outlet) sides of the pump 24 toplace the pump in fluid communication with the manifold body 31. Suchsuction and pressure hoses also incorporate press-in connectors forconvenience of the assembler.

[0058] Still referring to FIG. 6, added to the fluid circuit 30 are anumber of pathways formed in the manifold body 31 as well as a number offlow control and filtering components for routing fluid entering andexiting the manifold between the various fluid ports 32, 34, 36, 38, 50and 52. Referring now to FIGS. 6 and 8-11, in this exemplary embodiment,there are four such pathways including a drain path, generallydesignated 57, for flow of fluid as indicated by directional arrow 58(FIGS. 6 and 10), a recirculation path, generally designated 80, forflow of fluid as indicated by directional arrow 59 (FIGS. 6 and 8), asupply path, generally designated 93, for fluid flow as indicated bydirectional arrow 61 (FIGS. 6 and 11), and a dump path, generallydesignated 95, for fluid flow as indicated by directional arrow 63(FIGS. 6 and 9).

[0059] It will be appreciated that the manifold body 31 forms a threedimensional fluid circuit and that FIGS. 6 and 8-11 are represented in atwo-dimensional layout for ease of description and are not meant to belimiting in any manner. For instance, the fluid ports in FIG. 12 areshown on one side of the manifold body while the same ports are shown onmultiple sides of the manifold body in FIG. 6. In addition, in FIG. 6,the manifold body 31 is not depicted as a rectangular block as in FIG.12. These illustrations are merely to facilitate description of thepreferred embodiment. Other suitable port locations and pathways mayoccur to one of ordinary skill and still fall within the scope of thepresent invention.

[0060] With continued reference to FIGS. 6 and 8-12, each pathway 57,80, 93, and 95 is generally tubular in transverse cross section and madeup of adjacent passage segments bored into the manifold body 31 whichare configured with straight runs meeting at right angles and compactedto minimize the size of the manifold body and further reduce hose lengthrequirements between components coupled to the manifold body and overallhose length requirements of the servicing apparatus. Some of these rightangle segments project into or out of the plane of the paper and may notbe shown in FIGS. 6, or 8-11. It will also be appreciated, whenconsidered from end to end, portions of each pathway may extend outsidethe manifold body and include couplings or connectors of flexible orrigid material connected to one or more manifold ports.

[0061] With particular reference to FIGS. 6, 10, and 12, during a drainprocedure as will be discussed below, fluid is normally directed in thedirection of arrow 58 through the drain path 57 from the return port 34to the used fluid drain port 36 which may be connected to the used fluidcollection tank 40 via conduit 39. Such passage 57 is formed by an entrybore extending into the manifold body 31, viewed into the paper in FIG.6, from the return port 34 to enter a short pre-filter segment 64 whichturns downwardly at a right angle from the entry bore, toward anaperture (not shown) in the bottom side 35 of the body aligned with afluid entrance into an in-line filter 60 to direct fluid into thefilter. The filter 60 is coupled to a hollow, threaded nipple 67projecting from the bottom side 35 of the manifold. The nipple isscrewed into an opening in the bottom side of the manifold body andfurther extends outside the body providing a connective threaded stubfor the filter 60. After exiting the manifold through the bottomaperture to enter the in-line filter 60, the drain path 57 then reentersthe manifold body through the hollow nipple and projects upwardly intothe body into a pre-drain valve segment 69. About the midpoint of thebody 31, the pre-drain valve segment terminates at an inlet of atwo-position drain/bypass solenoid valve 70 which may be screwed into athreaded valve port 65 on the top side 33 of the manifold body 31 toposition the dual outlet valve 70 in line with both the drain path 58and recirculation path 80 of the fluid circuit 30. Such valve 70includes a drain position, indicated by directional arrow 66, whichdirects fluid entering the inlet of the solenoid 70 out of a drainoutlet of the solenoid 70 and through the remainder of the drain path 58(FIGS. 6, 10) and a normally open bypass position, indicated bydirectional arrow 68, which directs fluid entering the inlet of thevalve 70 out of an alternate outlet and through a recirculation path 80(FIGS. 6, 8).

[0062] The valves described herein are preferably two-position,three-way magnetic solenoid valves, either size 8 or 10, which may beenergized to enter into a number of alternative positions. Such valvesare available from Hydac Technology Corporation in Bethlehem,Pennsylvania. Other suitable valving arrangements for directing fluidflow to or from multiple channels may also be used.

[0063] With continued reference to FIG. 10, the drain path 57 turns at aright angle from the longitudinal centerline of the solenoid 70 into apost-solenoid segment 72 forming the stem of a T-shaped intersection 74.Then the path is bifurcated to, in one branch, enter into a used fluidconnection branch 75 of the T-shaped intersection leading to the drainport 36 which may be connected to the used fluid collection tank 40.Fluid entering the return port 34 from the serviceable component is thusnormally directed along this drain path 57 if the drain/bypass solenoid70 is energized to the drain position 66 for collection in the usedfluid tank 40.

[0064] Referring now to FIGS. 6 and 8, when the drain/bypass valve 70 isenergized to the bypass position as indicated by directional arrow 68,the recirculation path 80 is opened and the drain path 57 is blocked.The recirculation path 80 shares the same plumbing with the drain path57 up to the drain/bypass solenoid 70 including the return port 34,pre-filter segment 64, filter 60, and pre-valve segment 69. Continuingthrough the drain/bypass solenoid valve 70, when energized to the bypassposition 68, the recirculation passage 80 projects at a right angle tothe longitudinal centerline of the solenoid to form an L-shapedrecirculation loop leading to the exhaust port 32 which may be connectedto the transmission inlet. Fluid entering the recirculation path fromthe return port 34 is directed through the solenoid 70 set in the bypassposition 68 to exhaust port 32. Such recirculation path normally servesto circulate fluid in the direction indicated by arrow 59 between theserviceable component and the servicing apparatus and through the filter60 while bypassing the pump 24, used fluid tank 40, and new fluid tank42.

[0065] With continued reference to FIG. 6, and with particular referenceto FIG. 11, the fresh fluid supply passage 93 is formed by an entry boreextending into the manifold body 31 from the new fluid supply port 38 tothen turn at a right angle forming an L-shaped pre-supply valve segment82. The segments discussed herein are preferably bored into the manifoldbody during manufacture. Such segment terminates at a two-positiondump/supply solenoid valve 84 which is also screwed into a threaded port85 on the top side 33 of the manifold body 31 to position the valve 84in line with the new fluid supply passage 93 (FIG. 11) and the dumppassage 95 (FIG. 9) in the fluid circuit 30. Such valve 84 includes anormally open supply position, indicated by directional arrow 81, whichreceives fluid withdrawn from the new fluid supply tank 42 and directsit through the remainder of the supply path 93 (FIG. 11). Thesupply/dump valve 84 also includes a dump position, indicated bydirectional arrow 83, which receives fluid being dumped from the usedfluid tank 40 and directs such fluid on through the remaining portion ofthe new fluid supply passage as well (FIG. 9).

[0066] Continuing with the new fluid passage 93, a pre-suction portsegment 86 projects at a right angle to the longitudinal centerline ofthe solenoid 84 and further includes a second right angle turn leadingto the suction port 50 (FIGS. 6 and 11). The suction side hose 54connects the suction port to the suction side of the pump 24 and apressure side hose 56 connects the pressure side of the pump 24 with thepressure port 52 at the top side 33 of the manifold body 31 to positionthe pump 24 in line with the supply path 93 (FIG. 11) and also the dumppath 95 (FIG. 9) depending on the valve 84 position. Reentering themanifold body 31 through the pressure port, the new fluid supply passage93 projects downwardly through a pre-supply filter segment 87 to lead toan aperture (not shown) on the bottom side of the manifold body 31aligned with an entry hole in a supply filter 88. The supply filter 88is also connected to the manifold body via a hollow, threaded nipple 90on the under side 35 (FIG. 12) similar to the drain filter 60connection. Exiting the filter 88 through the hollow nipple 90, the newfluid supply path 93 projects upwardly into the manifold body 31 throughan in-line one-way check valve 92 and then turns outwardly toward theback side 37 of the manifold body in an L-shaped segment 94 leading tothe exhaust port 32 which may be connected to the transmission inlet orcollection tank via servicing hose 46. The final segment 94 of the newfluid supply path 93 leading to the exhaust port 32 is common with thelast segment of the recirculation path 80.

[0067] The check valve 92 is incorporated in the supply fluid circuit 93to prevent fluid from backflowing or otherwise entering the outlet ofthe supply filter 88 from the recirculation path. This feature alsoserves to keep the pump 24 primed in use. However, it is preferable toselect a suitable pump 24 having an integrated check valve forincorporation into the servicing apparatus 20 so that the external checkvalve 92 can be omitted altogether. The supply pathway 93 normallyserves to conduct fluid in the direction of arrow 61 from the freshfluid supply 42 connected to the new fluid port 38 and direct the fluidto the exhaust port 32 and to the upstream line of the serviceablecomponent via servicing hose 46 to supply fresh fluid thereto.Alternatively, such passage 93 can be used to drain the new fluid tank42 when the servicing hose 46 is coupled to a collection tank.

[0068] Turning now to FIGS. 6 and 9, the fluid circuit 30 also includesthe used fluid dump pathway 95 for transporting fluid in the directionof arrow 63 between the drain port 36 and the exhaust port 32 fordraining fluid from the used fluid tank 40 using the common pump 24.With continued reference to FIG. 9, the dump path 95 begins with at thedrain port 36 which is normally coupled to the used fluid collectiontank 40 via the used fluid conduit 39. The dump path 95 is then formedwith a bore projecting inwardly from the drain port 36 along a straightsegment to form the first branch 75 of the T-intersection 74. The path95 bifurcates at intersection 74 to flow through to a straight pre-valvesegment 91 to one inlet of the dual inlet dump/supply solenoid valve 84which controls the flow on to the outlet bore 86 (pre-suction portsegment) leading to the suction port 50 when the valve is energized tothe dump position 83. The remaining portion of the dump path is commonto the new fluid supply path 93 as it exits the solenoid 84 ultimatelyleading to the exhaust port 32 including passage through the outlet bore86 through the suction port 50 to the inlet of the pump 24 via coupling54. The fluid is then directed through the outlet of the pump 24 throughcoupling 56 to pressure port 52 on through filter 88, check valve 92 toexhaust port 32. Such path 95 normally serves to direct fluid withdrawnfrom the used fluid collection tank 40 in the direction of arrow 63using the common pump 24 to direct used fluid through the exhaust port32. Instead of connecting the service hose 46 to the transmission,however, the free end of the service hose is typically placed in a wastefluid receptacle (not shown) for future storage so that the used fluidtank 40 may be drained.

[0069] With continued reference to FIGS. 6 and 8-11, fluid typicallyenters the return port 34 from conduit 44 connected to the downstreamport of the transmission and exits the exhaust port 32 to be directedthrough hose 46 to the upstream port of the transmission. Fluid isgenerally circulated through the fluid circuit 30 by the single,non-reversible pump 24 interposed in the supply and dump pathways 93 and95, respectively, to complete these pathways. Fluid may also becirculated by a pump associated with the serviceable component throughthe drain and recirculation paths 57 and 80, respectively. Direction ofthe fluid through the fluid circuit 30 is normally determined by therespective positions of the single inlet, dual outlet, drain/bypassvalve 70 and dual inlet, single outlet, dump/supply valve 84. Thedrain/bypass valve 70 operates to direct fluid entering the return port34 through the drain or bypass passages 57 and 80 respectively with oneside of the valve 70 in fluid communication with the return port 34 andthe second side in fluid communication with the drain port 36 andexhaust port 34. When solenoid 70 enters into the drain position 66, thebypass passage 80 is blocked off and the passage between the return port34 and the drain port 36 is open and fluid may flow in the direction ofarrow 58 (FIG. 10). On the other hand, when the valve 70 is energized tothe bypass position 68, the drain passage 57 is blocked off and thepassage between the return port 34 and the exhaust port 32 is openestablishing a bypass loop 80 wherein fluid may circulate in thedirection of the arrow 59 and wherein fluid does not circulate throughthe pump 24 (FIG. 8).

[0070] Referring to FIGS. 6, 9, and 11, connected in fluid communicationwith the supply and dump paths 93 and 95, respectively, is thedump/supply valve 84 with the outlet of the valve in fluid communicationwith the exhaust port 32 and the dual inlet in fluid communication withthe drain port 36 and new fluid supply port 38. When the valve 84 isenergized to the supply position 81, the dump passage 95 is blocked offand the passage 93 between the new fluid supply port 38 and the exhaustport 32 is open so that fluid may flow in the direction of arrow 61(FIG. 11). On the other hand, when the valve 84 is energized to the dumpposition 83, the new fluid supply passage 93 is blocked off and thepassage between the drain port 36 and the exhaust port 32 is openestablishing a passage 95 for dumping fluid in a direction indicated byarrow 63 to be collected in the used fluid tank 40 by withdrawing suchfluid with the common pump 24 (FIG. 9). Selection of these valvepositions 66, 68, 81, and 83 is directed by the controller 28 and theoperator or service technician using the electrical command system aswill now be described.

[0071] Electrical Command Subsystem

[0072] Referring now to FIGS. 1-3, and 6, the heart of the electricalcommand subsystem is the controller 28 which is a programmable circuitboard having a central processing unit (CPU) and associated memory fortransmitting control commands to the pump 24 or valves 70, 84 inaccordance with command sequences stored in the memory responsive tofeedback transmitted from a number of sensors to direct the fluidservice operations selected by a service technician. In this exemplaryembodiment, there are three such sensors.

[0073] With particular reference to FIG. 6, the controller 28 isconnected to a new fluid tank sensor 100 and a used fluid tank sensor102 through their respective electrical leads 104 and 106 to providefluid level feedback for each tank, 42 and 40, respectively. The fluidlevel sensors detect the fluid level in their respective fluid tanks andprovide this information to the controller which includes tank geometricdata and fluid density data in its memory for calculating the volume offluid in each tank. Such fluid level sensors are preferably gas sensors,available from Motorola and constructed to monitor the air pressure ineach tank. A two-port balancer system is used so that the sensors candetect outside air pressure and take into account elevation of theservicing apparatus to provide more accurate fluid level readingsthereby compensating for discrepancies between sea level readings andreadings taken at other altitudes.

[0074] The controller 28 is also in electrical communication with apressure sensor 108 through electrical lead 110. Such pressure sensor108 is threaded into an aperture 109 on the top surface of the manifoldbody 31 and is used for sensing fluid pressure in the last segment 94 ofthe fluid circuit leading to the exhaust port 32 and providing feedbackto the controller 28 and is primarily used to detect incorrect servicehose connections during the drain procedure as will be discussed below.

[0075] With continued reference to FIG. 6, the pump 24, drain/bypassvalve 70, and dump/supply valve 84 are in electrical communication withthe controller 28 via their respective electrical connectors 112, 114,and 116. Using feedback from the sensors and any additional operatorinput, the controller energizes the first and second valves 70 and 84 tothe desired positions as will be described below and further actuatesthe pump 24 to on and off states during selected servicing procedures tocirculate the fluid through the fluid circuit 30 from the desired sourceto the selected destination. Conveniently, the controller 28, a controlpanel 130, valves 70 and 84, pump 24, and sensors 100, 102, and 108 arein electrical communication with a set of battery cables 120 (FIG. 1).Thus, power may be supplied to such components capable of being poweredby a 12 volt DC source by attaching a set of battery cables 120 to thevehicle's battery. It will be appreciated that such electrically poweredcomponents could also be hardwired to an alternative power sourcelocated on the servicing apparatus itself 20 or constructed to plug intoa wall outlet.

[0076] Referring now to FIGS. 1 and 2, in this exemplary embodiment, anoperator may interface with the controller 28 via a control panel 130located on a top forward inclined surface of the cabinet 22. Suchcontrol panel is generally divided into four regions including anoptions menu listing 132 presenting the available operational options, adisplay region 134 with a plurality of LEDs and a counter display 136for indicating machine and operational status and displaying quantity ordiagnostic information, an interactive control region 138 and a powersteering exchange (PSX) pendant dock region 140 for attaching a remotecontrol for controlling power steering fluid exchange operations whichwill be described in detail below.

[0077] With continued reference to FIG. 2, the options menu listing 132positioned to the left side of the control panel 130 includes a listingof procedural options 1-9, respectfully indicated as OP1-OP9 asimprinted or otherwise provided on the face of the control panel (FIG.2). The exemplary options are as follows:

[0078] OP1 Add 1 quart of fluid;

[0079] OP2 Remove 1 quart of fluid;

[0080] OP3 Drain new fluid tank;

[0081] OP4 Drain used fluid tank;

[0082] OP5 Access new fluid volume;

[0083] OP6 Access used fluid capacity;

[0084] OP7 Auto prime the system;

[0085] OP8 New fluid sensor check; and

[0086] OP9 Used fluid sensor check.

[0087] Such exemplary options, as illustrated in FIG. 2, are accessiblevia an options menu button 142 in the control region 138 and engageableby a start exchange/options button 144 as will be described below. Thedisplay region 134 provides visual feedback to the operator as to thestatus of the fluid exchange procedures and servicing apparatus 20operation. The primary indicator is the counter display 136 whichprovides a visual display of requested information such as the servicingoption being invoked, fluid capacities, or other information in the formof alphanumeric messages.

[0088] Continuing with FIG. 2, further comprising the display region 134are a number of LED indicators divided into four columns. The firstcolumn includes a quarts LED indicator 146 and a liters LED indicator148. Such indicators indicate the system of measurement being used. Nextto the first column is a column of amount indicators including a 20quart indicator 150, a 16 quart indicator 152, a 12 quart indicator 154,and a 4 quart indicator 156. Each of these indicators provides a displayto the operator as to the amount of fluid selected by the operator foran exchange. For purposes of an automatic transmission fluid exchange,eight cylinder, full size vehicles or truck typically require a twentyquart exchange. Mid-size vehicles with 6-cylinders typically require asixteen quart fluid exchange and compact, four cylinder vehiclestypically require a twelve quart exchange. Sub-compact vehiclestypically only require a four quart exchange.

[0089] Still referring to FIG. 2, the third column in the display region134 indicates machine operation status and includes a stopped indicator158, a halted indicator 160, a running indicator 162, a completeindicator 164, a switch hoses indicator 166, and a shift to neutralindicator 168. A machine status column is the fourth column in thedisplay region 134. Such machine status column includes a new ATF lowindicator 170, a used ATF full indicator 172, an add/remove ATFindicator 174, and a new/used ATF drain indicator 176. The meaning ofthese indicators will be discussed below when the operation of theservicing apparatus is described.

[0090] Spaced below the display region 134 in the control region 138 isa first and second set of depressible buttons for initiating a varietyof functions to operate the servicing apparatus 10 (FIG. 2). Theleftmost button of the first set is a quantity button 178 for selectingthe quantity of fluid to be transferred from one location to another.Depressing this button cycles through the quantity indicators 150, 152,154, and 156. Next to the quantity button is positioned theexchange/options button 144 for initiating a fluid exchange orinitiating the option selected by the options menu button 142. A powersteering button 180 for initiating a power steering fluid exchange isnext in line followed by the option menu button 142. The options menubutton cycles through the options listed in the options menu 132 whendepressed.

[0091] The leftmost button in the right hand set of buttons is an addATF button 182 for adding automatic transmission fluid where directed bythe fluid circuit 30. Next to the add ATF button is a remove ATF button184. Selection of this button may be used to remove or drain ATF fromthe selected source. The third button is a cycle sensors button 186 forcycling the valves 70, 84 between their respective positions to clearthe valves prior to operation of the servicing apparatus 20 to ensurethe valves are in proper working order. The last button is a stop button188 for shutting the apparatus down completely in an emergency or otherdesired stop condition. Such button is preferably a larger size orotherwise stands out from the other buttons so it may be rapidly locatedby the operator. An illustrative servicing procedure using theabove-described plumbing and electrical subsystems incorporated into aservicing apparatus 20 will now be described.

[0092] Operation of the Fluid Servicing Apparatus

[0093] In the field, the manifold assembly 26 is typically securedwithin an internal compartment of the servicing apparatus 20 using asuitable threaded fasteners screwed into a pair of mounting bores 194 onthe front side 43 of the manifold body 31 (FIGS. 1 and 12) and comespreassembled. Such internal compartment is accessible via a removableservicing panel 190. The pump 24 is also preferably secured inside theservicing apparatus. The control panel 130 is also removable and mayprovide an alternative access into the compartment. Near the bottom ofthe servicing apparatus, the used and new fluid tanks 40 and 42,respectively are placed on a convenient shelf.

[0094] While the servicing apparatus 20 is typically assembled prior tooperation of the servicing apparatus 20, it will be appreciated that theintegrated manifold assembly 26 has been designed to reduce assemblytime and facilitate servicing in the field and that some connection maybe required prior to initiating servicing procedures or duringmaintenance.

[0095] Referring now to FIGS. 3, 6, and 12, starting with the basicmanifold body 31 with preformed fluid circuit 30 and built-in couplingsthreaded into the ports 32, 34, 36, 38, 50 and 52, the operator mayconnect the used fluid conduit 39 by pressing one end into the drainport 36 and the other end is inserted into or otherwise coupled to theused fluid tank 40. The supply conduit 41 is likewise coupled betweenthe supply port 38 and the new fluid tank 42. The pump 24 may then beconnected to the top side 33 of the manifold body by pressing in one endof the suction hose 54 into the suction port 50 and its opposite endinto the suction side inlet of the pump 24. Similarly, one end of thepressure side hose 56 is pressed into the pressure port 52 its other endinto the pressure side outlet of the pump 24.

[0096] With continued reference to FIG. 12, the connector nipples of thevalves, pressure sensor, and filter components may then be screwed intotheir respective threaded ports on the manifold body 31. Morespecifically, the drain/bypass valve 70 is threaded into the port 65 toplace the valve inline with the drain and bypass fluid paths, 57 and 80respectively. The inlet of the valve 70 is aligned with the terminal endof the pre-filter bore 34. The first outlet of the valve 70corresponding to position 66 is aligned with the inlet to bore 72 andthe second outlet of the drain/bypass valve 70 corresponding to position68 is aligned with the inlet to the recirculation loop 80. Likewise, thedump/supply valve 84 is screwed into threaded port 85 on the upper side33 of the manifold body to place such valve in fluid communication withthe supply and dump paths, 93 and 95 respectively. The first inlet ofvalve 84 corresponding to position 81 is aligned with the exit ofpre-valve bore 82 and the second inlet of valve 84 corresponding toposition 83 is aligned with the exit to bore 91. The outlet of valve 84is aligned with the entrance to post-valve bore 86. The nipple of thepressure switch 108 is also threaded into its respective threadedaperture 109 on the top side 33. On the bottom side 35 of the manifoldbody 31, the filters 60 and 88 are screwed onto their respective nipples67 and 90 until their respective gaskets are flush with the undersurfaceof the manifold providing a suitable seal. The entry port of the drainfilter 60 aligns with the aperture occurring at the end of the pre-drainbore 34. The entry port of the supply filter 88 aligns with the apertureoccurring at the end presupply filter bore 87. The filters arepreferably of the ten micron absolute variety and the threaded nipplesare preferably constructed using metric threads to inhibit a servicetechnician from bypassing the filters. Such filters also act asmaintenance indicators as fluid servicing procedures will take longer asthe filters become more and more clogged obstructing fluid flow.

[0097] Each of the electrical leads of the pump 24, valves, 70, 84, andsensor 108 along with the other DC powered components may then be placedin electrical communication with the controller 28 and battery cables120 via the wiring harness.

[0098] When the service technician is prepared to service an automobiletransmission, with reference to FIGS. 1-3, and 6, the new fluid tank 42and used fluid tank 40 may initially be empty. The servicing apparatus20 is initially prepped for servicing by filling a quantity of newtransmission fluid through a fill hole (not shown) into the new fluidtank 42. For purposes of this operational procedure, it will be assumedthat the used fluid tank 40 is initially empty and the new tank 42 hasan adequate supply of transmission fluid to perform a complete exchange.The servicing apparatus 20 is wheeled over near the transmission to beserviced. Using well known procedures, the service technician interruptsthe transmission cooling lines to expose an influent line or inlet portand an effluent line or outlet port and connects the free ends to thereturn and exhaust ports 34 and 32 of the manifold assembly 26 using theservice hoses 44 and 46 using conventional adapters if necessary.Preferably, the technician connects the effluent line of thetransmission to the return port 34 and further connects the influentline at one end to the exhaust port 32 such that the connection placesthe transmission in fluid communication with the fluid passages 57, 80,93, and 95 of the servicing apparatus 20 (FIGS. 1, 6, and 8-11). It willbe appreciated that the service hoses 44, 46 are preferably clearallowing an operator to visually check the condition of the fluid ineach hose. The default position of the drain/bypass valve 70 is thebypass position 68 blocking off the drain path 57 so that fluid flowfrom the transmission will circulate through fluid passage 80 in thedirection of arrow 59 initially when the vehicle engine is turned on toactivate the transmission pump (FIG. 8).

[0099] With continued reference to FIGS. 6 and 8, once the service hoses44, 46 are connected, the technician may then connect battery cables 120to the vehicle battery to supply power to the control panel 130,controller 28, drain/bypass valve 70, dump/supply valve 84, pump 24,sensors 100, 102, 108, all of which are preferably selected to run on a12-volt DC power supply. Using the versatile servicing apparatus 20, thetechnician may perform several servicing procedures includingcirculation and clean, automatic transmission fluid exchange by drainingand refilling the transmission in incremental steps, draining andrefilling the transmission pan, topping off fluid levels, and drainingthe new and used fluid tanks. It will be appreciated that the followingprocedures are performed using only a single common pump 24 operating inconjunction with the vehicle transmission pump for some procedures.

[0100] In the initial stage after the service hoses 44 and 46 areconnected to the return and exhaust ports 34 and 32 and transmissioncooling lines, the operator may press the cycle sensors button 186 toactuate the valves 70 and 84 through their full range of movement toclear any obstacles, debris, or other contaminants that may preventperformance.

[0101] With battery cables 120 connected, the operator may start thevehicle engine to operate the transmission pump and to pressurize fluidout of the transmission to begin circulating fluid through circulationpassage 80. This is commonly referred to as circulation mode duringwhich the pressure switch 108 in normally inactive. Depending on thetransmission pump and direction of fluid flow, used fluid from thetransmission is forced out into the recirculation passage 80 from eitherthe return port 34 or the exhaust port 32. Fluid will either flow in thedirection of arrow 59 or in a reverse direction. The fluid exits therecirculation passage 80 from the opposite port wherein fluid isentering and reenters the transmission through the associated servicinghose. The check valve 92 prevents the used fluid from entering theservicing apparatus pump 24. At this point a closed circulation loopbetween the vehicle transmission cooling lines and servicing apparatus20 is established and the running indicator 162 lights up on the controlpanel 130. It will be appreciated that the used transmission fluid isdirected through the filter 60 to remove particulate from the used fluidduring this initial procedure.

[0102] While the fluid is circulating, the operator may then select thequantity of fluid to be changed via the control board 130 connected tothe processor/controller 28 by depressing the quantity button 178 untilthe indicator 150, 152, 154, or 156 beside the desired quantityilluminates (FIG. 2). Assuming for example, a full-sized 8-cylindervehicle is being serviced, the operator selects the 20 quart quantity bytoggling the quantity button until the desired indicator lights up. Inthis instance, the 20 quart indicator 150 will light up on the controlpanel. At this point, the pump 24 is not running and fluid is only beingcirculated by the transmission pump.

[0103] Turning now to FIGS. 2, 6, 8, and 10, having selected thequantity to be exchanged, the operator presses the startexchange/options button 144 on the control panel 130 of the servicingapparatus 20, which causes several actions to occur. Initially, thecontroller 28 energizes the drain/bypass solenoid 70 to move from thebypass position 68 to the drain position 66 to block off therecirculation passage 80 and open the drain path 57. If the servicehoses have been connected properly, used fluid entering the return port34 under pressure from the transmission pump is directed through thedrain path 57, along the direction of arrow 58, through the drain port36 and used fluid conduit 39 connected thereto to be collected in theused fluid collection tank 40. Once the valve 70 is energized to thedrain position 66, the controller 28 will take a reading of the usedfluid tank sensor 102 to sense the hydrostatic pressure head therein(FIG. 6). If no fluid is sensed in the used fluid tank 40, thecontroller will also take a reading of the signal transmitted from thepressure sensor 108 to determine if any fluid is entering the exhaustport 32 and is present in segment 94. With the signal stored showing nofluid in the used fluid tank, detection of fluid entering through theexhaust port 32 into the recirculation passage 80 is indicative of animproper hose connection. If that's the case, the processor 28 actsaccordingly to alert the operator of an improper hose coupling conditionby transmitting a signal to illuminate the switch hoses indicator 166 onthe control board 130. It will be appreciated that an audible alarm maybe programmed into the controller 28 to accompany this display or any ofthe displays to further alert the operator. The operator may then turnthe vehicle engine off and manually switch the service hoses 44 and 46between the respective ports 32 and 34. Once the hoses are switched theoperator restores the servicing apparatus 20 to circulation mode asdescribed above.

[0104] On the other hand, if a no pressure signal is transmitted by thepressure switch 108 to the processor after the drain process isinitiated and no fluid is detected by the sensor 102 in the used fluidtank 40, the shift to neutral indicator 168 is illuminated. Thisoccurrence may be due to the fact that, for instance, many Chryslertransmissions pump fluid only when in neutral. If the switch hosesindicator 166 and the shift to neutral indicator 168 have not lit, thenthe hoses are connected properly and proper fluid flow has beenestablished. The transmission may then be serviced.

[0105] Assuming these error conditions do not occur, when the startbutton 144 is pressed the transmission pump will force the fluid fromthe return port 34 through the filter 60 into the drain passage 57 andthrough the solenoid valve 70 set in the drain position 66 (FIGS. 6 and10). Used fluid passing through the solenoid 70 is directed to the drainport 36 in the direction of arrow 58 and expelled into the used fluidtank 40. The level sensor 102 in the used fluid tank transmits a signalproportional to the level of the fluid entering into the used fluid tankto the processor 28 by sensing the hydrostatic pressure head of thefluid entering the used fluid tank. The pressure head data is used tocalculate the volume of fluid in the used fluid tank as the knownparameters of the tank geometry and fluid density stored in theprocessor are recalled by a volume calculation routine. In thisexemplary embodiment, once {fraction (6/10)} of a quart is collected inthe used fluid tank 40 as calculated by the processor 28, the processorwill energize the drain/bypass solenoid 70 to reenter the bypassposition 68 blocking off the drain passage 57 and forcing the fluid intothe recirculation passage 80 in the direction of the arrow 59. Otherpredetermined quantities could also be used. The processor 28 theninitiates an incremental fill mode.

[0106] Turning now to FIGS. 2, 6, and 11, to perform the incrementalfill portion of the process, the processor 28 will actuate thedump/supply solenoid 84 to cause it to assume the supply position 81 toopen the new fluid supply path 93 from the new fluid tank 42 through theservicing apparatus pump 24 to the exhaust port 32 to the transmissionvia servicing hose 46. The processor also actuates the pump 24 at thistime withdrawing fluid from the new fluid tank 42 in the direction ofarrow 61 and through the suction port 50 and suction hose 54 to thepump. Fresh fluid is then pumped out of the pump through the pressurehose 56 to pressure port 52. Such fresh fluid is directed under pressurethrough the supply filter 88 and one-way check valve 92 and, because itcan not enter the drain/bypass solenoid 70 due to incoming fluidpressure, is directed through the exhaust port 32 to the vehicle'stransmission via service hose 46. When the level in the new fluid tankis lowered an amount corresponding with {fraction (6/10)} of a quart,the level sensor 100 will transmit a signal to the processor 28 which isprogrammed to respond to shut off the internal pump 24 and then shiftthe drain/bypass solenoid 70 back into the drain position 66 to repeatthe incremental drain procedure.

[0107] This drain then fill process continues in an alternating,iterative manner as the processor 28 periodically responds to discretedrops in the level of fluid sensed by the fluid sensor 100 in the newfluid tank. When the quantity of the new fluid transferred out of thenew fluid tank equals the preselected quantity initially set by theoperator, and indicated by one of the quantity indicators 150, 152, 154,or 156, the processor will energize an exchange complete indicator 164on the control board 130 and actuate an audible signal (FIG. 2). Theprocessor 28 then shifts the drain/bypass solenoid 70 to the bypassposition 68 to switch the servicing apparatus 20 to the recirculationmode and circulates fluid through the recirculation passage 80. Asbefore, during recirculation mode, the internal pump 24 is deactivated.

[0108] In this exemplary procedure, the processor is operative to, indiscrete {fraction (6/10)} quart increments, transfer a total of 20quarts of fluid to the used fluid tank 40 and an equal volume of newfluid is withdrawn from the new fluid tank 42. Responsive to theexchange complete indicator, the operator will turn the engine off anddisconnect the service hoses 44, 46 from the servicing apparatus 20. Theoperator will then reconnect the vehicle transmission cooling loop tocomplete the servicing procedure. It will be appreciated that upon theoperator depressing the start button 144, the entire fluid exchangeprocedure will be performed automatically without further operatorintervention until he or she turns the engine off and reconnects thetransmission cooling lines, assuming no error in connection wasdetected. In addition, to prevent an overpressure condition during fluidexchange or other servicing procedures, a pressure relief valve (notshown) may be placed in communication with the fluid circuit 30 and setto relieve in response to a preselected pressure to route overpressurized fluid through a bypass. It will be appreciated that thealternating drain and fill exchange process takes place rapidly and anentire exchange for an eight cylinder vehicle can take place inapproximately 10-15 minutes.

[0109] Such fluid exchange will typically leave the new fluid tank 42empty or partially empty and the used fluid tank 40 partially full orcompletely full depending on the tank capacity. Should the operator thenattempt to start another servicing procedure and select an exchangequantity that exceeds the amount of fluid remaining in the new fluidtank 40, the processor 28, having taken a reading of the new fluidsensor 100, will transmit a signal to the control board 130 toilluminate the new ATF low indicator 170 to alert the operator thatthere is insufficient fluid in the new fluid tank 42 to perform theselected procedure (FIGS. 2 and 6). To refill the new fluid tank 42, theoperator may supply new fluid through its fill hole. During thisprocedure, the processor functions to illuminate the Add/Remove ATFindicator 174 alerting the operator that fluid is being added to the newfluid tank 42.

[0110] On the other hand, should the operator select an exchangequantity that would overflow the capacity of the used fluid tank 40, theprocessor, having taken a reading of the used fluid sensor 102, willtransmit a signal to the control board 130 to illuminate the used AFTfull indicator 172 alerting the operator to drain the used fluid tankbefore proceeding. Conveniently, the fluid circuit 30 and common pump 24enable such draining or dumping of the used fluid tank 40 without theassistance of a dedicated drain pump.

[0111] Referring now to FIGS. 1, 2, and 9, to initiate the used fluiddump procedure, the operator will connect one end of the servicingconduit 46 to the exhaust port 32 and place the free end of theservicing conduit into a fluid waste tank (not shown). The operator willthen depress the options button 142 on the control panel 130 to scrollthrough the options menu (OP1-OP9) until the desired option is displayedin the counter display 136. In this scenario, the OP4 option code wouldbe displayed in the counter display 136 indicating that the operator haselected to drain the used fluid tank. Conveniently, the operator mayrefer to the option menu 132 imprinted on the left side of control panel130 to determine the procedure associated with the option code. Next,the operator may engage the start button 144 to begin the used fluiddumping procedure. In response to the operator's command, the controller28 energizes the dump/supply valve 84 to its dump position 83 to openthe dump passage 95 and then actuates the pump 24 to begin drawing fluidfrom the used fluid tank 40 through the open dump passage in thedirection of arrow 63. The fluid is expelled through the exhaust port 32through the servicing conduit 46 and into the storage receptacle. Oncethe controller 28 detects the used fluid tank is at a predeterminedbottom operating level via the used fluid level sensor 102, thecontroller will shut the pump 24 off and terminate the procedure. Bypressing the start button 144 for five seconds the operator can effectdraining of the used fluid collection tank 40 until the stop button 188is pressed. An audible alarm sounds when the used fluid tank level isempty as sensed by the used fluid sensor 102 and illumination of thecomplete indicator 164 on the control panel 130 alerts the operator thatthe dump procedure is completed. It will be appreciated that theplumbing circuit of the exemplary embodiment enables draining of theused fluid tank without the necessity of inverting the tank upside downto drain from its top end or incorporating an extra dedicated drain pumpto draw the used fluid from the used fluid tank and direct it to a wastefluid collection receptacle.

[0112] In a similar manner, the new fluid tank 42 may also be drainedcompletely as desired. Referring now to FIGS. 1, 2, 6, and 11, asdescribed for the used fluid tank 40 dumping procedure, one end of theservicing conduit 46 may be connected to the exhaust port 32 and itsfree end placed into a new fluid storage receptacle (not shown). In thisscenario, the operator may toggle the options button 142 until OP3 isdisplayed in the display counter 136. Activation of the exchange/optionsbutton 144 will cause, the controller 28 to shift the dump/supply valve84 to its supply position 81. The pump 24 is also actuated and fluid isdrawn from the new fluid tank 42 along the supply passage 93 in thedirection of arrow 61 to be expelled through the exhaust port 32. Theexpelled fluid is transferred through the servicing hose 46 to the newfluid receptacle for storage. The processor 28 is responsive to thesensor 100, sensing that the fluid level in the new fluid tank hasfallen to a predetermined bottom operating level to shut the pump 24 offand terminate the drain new fluid procedure. The operator may then pressand hold the start button 144 for five seconds to initiate a full drainof the new fluid tank 42 until the stop button 188 is pressed. Anaudible alarm sounds when the new fluid tank level is empty as sensed bythe new fluid sensor 100 and the complete indicator 164 is illuminatedby the processor on the control board 130 (FIG. 2).

[0113] Turning now to FIGS. 2 and 6, it will be appreciated that theoperator may check the new fluid volume and used fluid capacity ascalculated by the controller 28. To display the new fluid volume in thenew fluid tank 42, the operator may depress the options button 142 andscroll through the options menu until OP5 is displayed in the counterdisplay 136. The operator may then simply depress the startexchange/options button 144 and the new fluid level sensor 100 sends asignal to the controller 28 which processes the signal and displays thenew fluid level in the counter display 136 in the measurement selected(quarts or liters). Likewise, to check the remaining capacity in theused fluid tank 40, the operator may select OP6 using the options menubutton 142 and then depress the start button 144. The used fluid levelsensor 102 will detect the used fluid level in the used fluid tank 40and transmit the corresponding signal to the controller 28. The signalis processed and the remaining capacity is calculated and displayed onthe counter display 136. These features may be used by the operatorprior to initiating a servicing sequence or in response to an indicatorlight from the control panel concerning fluid levels or any other timeas selected by the operator.

[0114] With continued reference to FIGS. 1 and 6, prior to beginning aservicing sequence, the operator may desire to auto prime the servicingapparatus 20. This feature is used to purge air out of the system.Preferably, at least six quarts of new fluid must be present in the newfluid tank 42 to initiate this procedure. After ensuring the properfluid level in the new fluid tank, the operator connects one end of eachservicing hose 44 and 46 to the respective return and exhaust ports 34,32 and connects the free ends of the hoses together with a priming hose(not shown) to complete the circulation loop. The operator then selectsOP7 by toggling the options menu button 142 and then depresses the startbutton 144. During the auto prime procedure, the controller 28 willactuate the pump 24 to begin drawing fluid from the new fluid tank 42through the supply path 93 and expelling fluid through the exhaust port32. The expelled fluid is transferred through the servicing hoses 46 and44 and interconnecting priming hose (not shown) to the return port 34.During this fluid transfer, the controller 28 cycles the drain/bypassvalve 70 between first and second positions 66 and 68, respectively tobuild up bursts of pressure to purge unwanted air in the servicingapparatus 20. Once three quarts of fluid have been transferred to theused fluid tank 40, the procedure is terminated by the controller 28.Such procedure is typically initiated prior to a fluid exchange.

[0115] Referring now to FIG. 2 and 6, another set of features engageablethrough the control panel 130 include filling the and drainingtransmission pan without removing the pan. In order to perform a quickfill of the transmission pan, the servicing hose 46 is connected betweenthe exhaust port 32 and an interrupted influent cooling line or fillingport of the transmission. The operator may then select OP1 using theoptions menu button 142 and depress the start button 144 to initiate theprocess. The controller 28 energizes the dump/supply valve 84 to thesupply position 81 and actuates the pump 24 to transfer fluid from thenew fluid tank 42 in a one quart increment to the transmission (FIG.11).

[0116] To drain the transmission pan, the servicing hose 44 is connectedbetween the return port 34 and an interrupted effluent transmissioncooling line or outlet. OP2 is selected by the operator using theoptions menu button 142 and the operator may then depress the startbutton 144. Drain/bypass valve 70 is energized by the controller 28 todrain position 66 establishing an open drain path 57 (FIG. 10). Theoperator may then turn the vehicle ignition on to start the transmissionpump forcing fluid out through the transmission effluent line and intothe return port 34 through the drain path 57, in the direction indicatedby arrow 58, to be collected in the used fluid tank 40. Once a quart hasbeen removed as detected by the used fluid level sensor 102 anddetermined by the processor 28, the complete indicator 164 on thecontrol board illuminates alerting the operator to terminate theprocedure.

[0117] Two other options may be used to check the new and used fluidsensors 100 and 102, respectively. To access the new fluid sensor check,the operator may access the options menu 132 by depressing the optionsmenu button 142 until OP8 is displayed in the counter display 136. Theoperator then depresses the start exchange/options button 144. The newfluid level sensor 100 will transmit a signal to the controller 28corresponding to the fluid volume in the new fluid tank 42. An absolutereading, which is typically between 300 and 4096 fluid units, will bedisplayed on the display counter 136. The start button 144 is thendepressed again to zero the absolute reading. A measured quantity of newfluid such as one quart is poured into the new fluid tank 42 through thefill hole. A new reading corresponding to the amount of fluid pouredinto the new fluid tank is measured by the processor 28 via the newfluid sensor 102 and displayed on the counter display 136. For example,if one quart is added, the counter display 136 should read 78 fluidunits. Any other reading indicates the sensor may need to be replaced orrecalibrated.

[0118] A similar procedure may be used to check the used fluid levelsensor 102. In this scenario, the operator selects OP9 in the displaycounter 136 using the options menu button 142 and depresses the startbutton 144. An absolute reading is displayed and then zeroed bydepressing the start button 144 again. A known quantity of fluid ispoured into the used fluid tank 40 which is measured by the used fluidlevel sensor 102 and displayed on the display counter 102. If thequantity displayed does not correspond to the amount poured in then theoperator is alerted that the used fluid sensor may need to be replacedor recalibrated.

[0119] Another convenient feature programmed into the controller 28 isthe totalizer. Such feature keeps track of the number of fluid unitspassing through the servicing apparatus 20. The total amount may bedisplayed in the display counter 136. As the display counter may onlydisplay a certain number of digits, a separate rollover counter isdisplayed indicating how many times the counter has reached itsnumerical limit. For example, if two digits were dedicated to thetotalizer display, a display reading of “2” is displayed initially andis followed by a “78”. Such display indicates the servicing apparatushas circulated 278 quarts of fluid. Advantageously, this feature enablesthe operator to develop a maintenance or replacement plan for theservicing apparatus 20 and its components. This feature is accessiblethrough depressing the stop button 188 for approximately 5 seconds.

[0120] The capability for smaller increment level adjustments is alsoconveniently built into the servicing apparatus 20. For example, ifduring an exchange operation, the operator elects to top off thetransmission fluid level with the hose 46 connected between the exhaustport 32 and the transmission influent line or inlet, the operator maydepress the add ATF button 182 on the control panel 130 (FIG. 2). Inresponse, the controller 28 commands the dump/supply valve 84 to thesupply position 81 and further commands the pump 24 to actuate such thata predetermined amount of new fluid is transferred along the supply pathto the transmission (FIG. 11). It has been found that about {fraction(2/10)} of a quart is a sufficient amount for such incremental fluidtransfers although it will be appreciated that other suitable levels maybe used. Once the predetermined amount has been removed from the newfluid tank 42, the controller 28 shuts the pump 24 off to terminate thetransfer.

[0121] To withdraw a relatively small increment of used fluid from thetransmission, the operator selects the remove ATF button 184 on thecontrol panel 130 while the vehicle transmission is running and the hose44 is connected between the return port 34 and the transmission effluentline or outlet (FIGS. 2 and 10). The controller 28 will then command thedrain/bypass valve 70 to assume the drain position 66 such that usedfluid is transferred from the transmission under the pressure of thetransmission pump through the return port 34 to the used fluid tank 40in the direction of arrow 58 through the drain path 57 upon turning thevehicle engine on. Once a {fraction (2/10)} of a quart or otherpredetermined increment is added to the used fluid tank 40, thecontroller 28 actuates the valve 70 to bypass position 68 to direct thefluid through the bypass/recirculation pathway 80.

[0122] It will be appreciated that the present embodiment is designed todetect reverse flow without harming the apparatus, transmission, oroperator, and to prevent fluid exchange until the fluid flow isconducted in a direction wherein the effluent flow from the transmissionpasses into the return port 34 and the influent flow to the transmissioncomes from the exhaust port 32. While such features have been providedin the servicing apparatus 20 to minimize operator intervention andfacilitate maintenance of the servicing apparatus and alert the operatorto error conditions, as discussed above, it is contemplated that anoperator may on occasion inadvertently couple the service hoses 44 and46 between the transmission and servicing apparatus 20 incorrectly thuscreating a reverse fluid circulation condition. While this may beadequately handled as described above with an alert to the operator,other ways of handling this condition are also contemplated by thepresent invention.

[0123] Cross Flow Operation

[0124] As discussed above, it is foreseeable that an operator mayinadvertently connect the hoses 44 and 46 improperly and upon initiatingan exchange procedure, a switch hoses indicator 166 would illuminate onthe control board 130 to alert the operator to the error conditionindicating that fluid is flowing in a direction opposite to direction ofarrow 59. The operator may then turn the engine off and manually switchthe hoses 44 and 46 by disconnecting and reconnecting them to the properreturn and exhaust ports 34 and 32. The technician may then restart thevehicle and initiate the fluid exchange as described above.

[0125] Referring now to FIG. 7, wherein like components are likenumbered, a second exemplary embodiment of the present inventionincludes an alternative manifold body 231 for avoiding the necessity ofmanually switching the hoses 44 and 46. In general, this alternativeembodiment is constructed the manner as the first manifold body 31described above with the exception that an alternative valve 270 hasbeen substituted in place of the drain/bypass valve 70 of the firstembodiment. Such alternative valve 270 is preferably a 3-position,4-way, magnetic solenoid valve with cross flow capabilities. Thecrossflow valve 270 includes a normal fluid exchange position, indicatedby directional arrows 272, a bypass position, indicated by a U-shapedsymbol 274, and a cross flow fluid exchange position, indicated bydirectional arrows 276.

[0126] With continued reference to FIG. 7, when energized to the normalfluid exchange position 272 by the processor 28, used fluid entering thereturn port 34 is transferred to the used fluid tank 40 and new fluidwithdrawn from the new fluid tank 42 may be transferred to the exhaustport 32 in a manner similar to that described above in the firstembodiment. This is effectively the same as the fluid exchange flowalong the drain path 57 and supply path 93 as in the first embodiment asillustrated in FIGS. 6, 9, and 11.

[0127] If, however, the controller 28 energizes the alternative valve270 to the bypass position 274, the servicing apparatus 20 is placed ina bypass/recirculation mode similar to the recirculation path 80illustrated in FIG. 8. Thus fluid may be circulated between thetransmission and servicing apparatus as described above with servicehoses 44 and 46 connected between the return port 34, exhaust port 32and transmission influent and effluent lines. Fluid being circulatedduring this mode may circulate in either direction as determined by theflow from the transmission.

[0128] Referring now to FIGS. 2, 7, and 13-14, in those instances wherethe operator has incorrectly coupled the servicing hoses 44 and 46 tothe servicing apparatus 20 so that used fluid enters through the exhaustport 32 instead of the return port 34 and the start button 144 on thecontrol panel 130 is depressed, the controller 28, upon receiving asignal that no fluid is entering the used fluid tank 40 and detectingfluid pressure via the pressure sensor 108, reacts accordingly byenergizing the crossflow valve 270 to assume its cross flow position276. As shown in FIGS. 7 and 14, in this position, it will beappreciated that fluid entering through the exhaust port 32 will bedirected through the solenoid 270 to cross over to the drain path,generally designated 257, to flow in the direction indicated by arrow258, where the used fluid may then be expelled through drain port 36 tobe collected in the used fluid tank 40. In such scenario, service hose46 is an inhose and port 32 is an inflow port. Likewise, new fluidsupplied from the pump 24 in the supply path, generally designated 293,to flow in the direction indicated by arrow 261, and passing throughfilter 88 flows through the check valve 92 and cross over valve 270 andis directed to the return port 34 which in this scenario operates as anoutflow port and hose 44 is an outhose (FIGS. 7 and 13). With thesolenoid 270 configured in the cross position 276, normal transmissionfluid exchange procedures may be performed as described for the firstembodiment above. Thus, it will be appreciated that such valve 270enables the operator to connect the hoses 44 and 46 without concern asto the flow direction as determined by the transmission configuration.Once the controller 28 establishes the proper valve position 272, 274,or 276, all servicing procedures may be performed as described above forthe first embodiment.

[0129] Referring now to FIGS. 15-16, wherein like components are likenumbered, an alternative valving component, generally designated 300,may be used in conjunction with a plumbing circuit, such as thatillustrated in FIG. 6, to provide normal drain, supply, and fluidexchange capability as well manually controlled cross over flowcapability in the event the servicing hoses 44, 46 are coupledincorrectly to the return port 34 and exhaust port 32 of the servicingapparatus 20.

[0130] In general terms, the manual cross over valve 300 includes arectangular housing 301 mounted to the manifold 31 of the servicingapparatus 20 using conventional fasteners such that an inner surface 303of the housing abuts the manifold 31 and an outer surface 306 projectsoutside the cabinet 22 exposing an auxiliary return port 308 and anauxiliary exhaust port 310 which are constructed similarly to the returnport 34 and exhaust port 32 to receive the free ends of the servicinghoses 44 and 46. The inner surface 303 of the housing 301 includes afirst passthrough port 302 aligned with the inlet to the return port 34and a second passthrough port 304 aligned with the outlet of the exhaustport 32 of the manifold 31. Alternatively, rigid or flexible fluidcouplings may be connected between the passthrough ports and the exhaustand return ports to provide fluid communication therebetween. Thus, thevalve 300 does not have to be mounted directly to the manifold. Each ofports 302, 304, 308, and 310 projects inwardly from their respectiveinner or outer surfaces into the housing and terminates at a central,cylindrical bore 312 projecting longitudinally throughout the housingfrom an open end 314 to a closed end 316. Thus fluid entering any one ofthese ports may be communicated inwardly to the central bore 312. Withinthe bore 312 partially resides a cylindrical plunger 318 or valve bodyincluding a hollow elongated section 320 slidably received in the boreand which transitions to an enlarged push/pull knob 322 near the openend 314 of the bore. The knob is positioned outside the housing foraccess by the operator to manually move the plunger through the bore. Areduced diameter stem 324 projects along the length of the elongatedsection between an enlarged flared end 326 proximate the closed end 316of the bore 312 and an opposing enlarged elongated locking end 328proximate the open end 314 of the bore. The outer surface of the lockingend includes a normal position detent 330 and a cross flow positiondetent 332 which cooperate with a ball bearing 334 forced outwardly by acoil spring 336 set in a slot 338 projecting radially outwardly from theinner surface of the bore 312 to releasably lock the plunger in a normalflow configuration (FIG. 15) or a cross flow configuration (FIG. 16).

[0131] A fluid transfer gap 340 is formed between the inner surface ofthe central bore 312 and outer surface of the reduced diameter stem 324.The plunger 318 further includes a cross over diverter port 342 whichmay be aligned with the second passthrough port 304 to receive fluidexiting the exhaust port 32 and entering the second passthrough portinto a cross over canal 344 projecting through the hollow plunger. Thecross over canal may direct fluid entering the diverter port 342 throughthe plunger and out of the open end 346 of the plunger near the closedend 316 of the central bore 312 where the fluid may then be directed outthe auxiliary return port 308. Inner, middle, and outer O-rings 348,350, and 352 inhibit undesirable leakage of the fluid from the housing301.

[0132] As will now be described, the plunger 318 and housing 301cooperate to form a two-position manually controlled valve to be used inconjunction with the manifold 31. Referring now to FIG. 15, in normaluse, the plunger 318 is selectively positioned by the operator graspingand pulling the knob 322 away from the housing 301 such that the ballbearing 334, as forced outwardly by the coil spring 336, nests partiallywithin the inner detent 330. The servicing hose 44 is connected from thetransmission outlet to the auxiliary return port 308 and the servicehose 46 is connected between the transmission inlet and the auxiliaryexhaust port 310. Assuming the hoses have been connected properly, inthis normal valve configuration, fluid exiting the return hose 44 isdirected into the auxiliary return port 308 along the direction of arrow354 and into first passthrough port 302 and then is directed into returnport 32 of the manifold 31 where the fluid may continue along the drainpath or recirculation path as described above. It will be appreciatedthat in this normal configuration, fluid is blocked from exiting thecross over canal 344 as the diverter port 342 is not aligned with any ofthe ports in the housing. In addition, in this normal configuration,fluid exiting the exhaust port 32 of the manifold 31 is directed intothe second passthrough port 304 and into the fluid transfer gap 340around the reduced diameter stem 324 in the direction of arrow 356 toflow out the auxiliary exhaust port 310 and into the service hose 46.Such fluid may then be directed into the transmission or a wastecollection tank as described above. In this configuration, the valve 300merely acts as a passthrough for fluid entering and exiting the manifoldfrom and to the servicing hoses.

[0133] Referring now to FIG. 16, if an alert of an improper hoseconnection is issued by the processor 28 from a reading of the usedfluid tank 40 (FIG. 6) and pressure sensor 108 after the operatorselectively initiates the fluid transfer process as described above, theoperator may manually shift the plunger 318 by grasping the knob 322 andpushing it inwardly into the housing until the ball bearing nestspartially within the cross flow detent 332. In this condition, servicehose 44 is an outhose instead of an inhose and service 46 is an inhoseinstead of an outhose. With the plunger positioned for cross flowconfiguration, the diverter port 342 is aligned with the secondpassthrough port 304 and the first passthrough port 302 blocked off fromthe auxiliary return port 308, and thus fluid exiting service hose 46,as forced by the transmission pump, may be directed into auxiliaryexhaust port 310, now providing a return port, and into the fluidtransfer gap 340 around the stem 324 along directional arrow 358 andinto the first pass-through port 302. The fluid is then directed intothe return port 34 of the manifold 31 to be directed normally along thedrain or bypass paths as described above. Fluid exiting the exhaust port32 flows into the second passthrough port 304 to the diverter port 342and into the transfer canal 344 along directional arrow 360. Such fluidexits the hollow end of the plunger along directional arrow 362 and outthe auxiliary return port 308, now providing an exhaust port, and intoservice hose 44 to the transmission. Other than this adjustment if theservicing hoses 44 and 46 have been improperly connected, the servicingapparatus 20 is operated as described above.

[0134] While the above described embodiments serve particularly well inservicing automatic transmissions, the present invention furthercontemplates servicing other automobile fluid systems as well andprovides such convenience in a single portable wheeled apparatus.

[0135] Power Steering Fluid Servicing

[0136] For example, referring now to FIGS. 4-5, another embodiment ofthe present invention will now be described. When an automobile is takenin for transmission servicing, it is typically necessary and convenientto exchange the power steering fluid at the same time. Advantageously,the present invention may incorporate additional plumbing to facilitatesuch a power steering fluid exchange. FIG. 4 illustrates the additionalplumbing for adding fluid to the power steering fluid reservoir (notshown). Such new power steering fluid (PSX) circuit, generallydesignated 200, is a conduit or servicing hose with several inlinecomponents including a new power steering fluid tank 204 preferablyhaving at least a two quart capacity, a new fluid filter 206, and a newpower steering fluid pump 208 in fluid communication with one anotherand terminating at one end in a coupling 210 or free end for insertinginto the open fill hole of the power steering reservoir. An inline ballvalve 223 is provided proximate the hose end to open and close the PSXsupply circuit 220 and prevent residual fluid in the conduit fromleaking out inadvertently.

[0137] Turning now to FIG. 5, for removing fluid from the power steeringreservoir, a PSX drain circuit, generally designated 220 is alsoprovided. Such drain circuit is a servicing hose or conduit with severalinline components including a drain pump 222, a used PSX filter 224 andterminating at one end in a coupling 222 or free end for insertion intothe power steering fluid reservoir. An inline ball valve 225 is providedfor opening and closing the drain circuit for similar purposes to ballvalve 223. The other end of the PSX drain circuit is convenientlycoupled to the used fluid tank 28 (FIG. 6) so that one common tank mayaccept either used transmission fluid or used PSX fluid. Such PSX supplypump 208 and PSX drain pump 222 are connected to the controller 28 (FIG.6) which may actuate either pump. The PSX supply and drain pumps mayalso be powered by the battery cable 120 connection to a 12 volt DCpower source such as the vehicle battery.

[0138] Referring now to FIG. 2, the operator may depress the powersteering button 180 located on the control panel 130 to initiate a powersteering fluid exchange by setting the servicing apparatus 20 in PSXmode. Alternatively, the power steering exchange may be performed usinga remote pendant 230 having an “ADD” button 221 and a “DRAIN” button 227(FIG. 1). Such pendant may be directly connected to the controller 28via suitable electrical cabling or communicate with the controller usingwireless technology including radio frequency or infrared communication.It is further contemplated that the ball valves 223, 225 may be coupledto the pendant 230 and remotely actuatable. Conveniently, when not inuse, the pendant is releasably retained on the control panel using aremovable magnetic holder 229 placed on the control board 130 in thependant dock region 140 (FIGS. 1 and 2).

[0139] In operation, and with particular attention to FIGS. 1-2, 4 and5, to exchange the power steering fluid in the power steering fluidreservoir, the following exemplary procedure may be used. The apparatus20 is initially wheeled over near the vehicle and the operator attachesthe battery cables 120 to the vehicle battery providing power to theservicing apparatus 20 and drain and supply pumps 208, 222. The operatormay then depress the power steering button 180 to set the servicingapparatus 20 into power steering fluid exchange mode. “PS” will displayin the display counter 136 on the control board 130 to indicate powersteering mode is engaged. The cap of the power steering reservoir, andany screen, is removed. The operator may then start the vehicle ignitionto start the engine running. The PSX drain coupling 222, which may be anopen hose end is placed inside the power steering reservoir as is thesupply coupling 210, also an open hose end. The hoses are preferablyequal in length and are disposed near the bottom of the power steeringfluid reservoir and are maintained at all times beneath the top fluidlevel in the fluid reservoir. Each ball valve 223, 225, of therespective supply and drain circuits 200, 220 are opened fully.Conveniently, the remote pendant 230 may be removed from its holder 229and held by the operator to extend operator mobility. The magneticholder may then be used to hold the hoses of the drain and supplyconduits in place to prevent the hoses from tangling. With the ballvalves 223, 225 open, the operator depresses the Add and Drain buttons221, 227 on the pendant 230 alternately to repeatedly drain and fill thereservoir while observing the fluid level in power steering fluidreservoir (FIGS. 1, and 4-5). This flushes the old fluid out of thereservoir. With the engine still running, the operator turns thesteering wheel fully to the left and right and then back to the centerand then checks the fluid color in the reservoir. Using the pendantallows the operator to move between the steering wheel and fluidreservoir. The alternating drain and fill step and wheel turning stepare repeated until a satisfactory fluid color is observed. During thisprocess, the processor 28 monitors the used fluid tank 40 level via theused fluid sensor 102. If a used fluid tank overflow condition isanticipated, the processor 28 disables the drain button 227 on thependant, illuminates the used fluid full indicator 172, and sounds analarm.

[0140] Once the operator notes the desired fluid color indicating theexchange is complete, the operator may depress the ADD button 221 on thependant to top off the power steering fluid reservoir. Alternatively,the operator may observes bubbles in the power steering fluid reservoirindicating that the new fluid supply has been exhausted. The operatormay then turn off the engine off and replace the cap and screen, if any,on the power steering fluid reservoir. Depressing the power steeringbutton 180 again resets the servicing apparatus to automatictransmission fluid exchange mode. It is apparent that the remote pumpactuator conveniently allows the operator to move back and forth betweenthe vehicle steering wheel and the power steering fluid reservoir asnecessary.

[0141] It will be appreciated that system described herein is capable ofperforming a number of operations including draining the used ATF fluidfrom the transmission, adding new ATF fluid to the transmission,draining the used fluid tank, draining the new ATF tank, using a singlecommon pump coupled to a fluid circuit provided by an integratedmanifold assembly constructed to minimize assembly time. Additionalplumbing features may also be introduced to perform cross flowsituations as well as service the power steering reservoir with aservicing apparatus incorporating a minimal amount of components.

[0142] The common pump 24 is preferably a one-way 130 psi pump availablefrom Shur-Flo. The power steering drain and fill pumps 208, 220 are alsoavailable from Shur-Flo and of a 45 psi variety. Other suitable pumpvarieties may also be used. The pressure switch is preferably set toabout 6 psi and is available from the Nason Company.

[0143] It will be appreciated that the drain path 58 (FIG. 10) betweenthe return port 34 and drain port 36 is formed almost entirely withinthe manifold body as is the recirculation path 59 (FIG. 8) between thereturn port 34 and exhaust port 32. Such paths only exit the manifoldbody to enter filter 60. In addition, much of the dump and supply path61, 63, respectively, lengths are formed within the manifold body 31 aswell with only a relatively short segment extending outside the manifoldbody to pass through the pump 24 or filter 88. Incorporation of a numberof right angles in the pathways is formed using three longitudinallyprojecting bores which are perpendicular from the passages projectingfrom the ports on the rear and top surfaces of the manifold body 31. Thebores ends are plugged during manufacture 192. By forming most of thefluid circuit within the manifold body, the hose length requirements aresignificantly reduced and the drawbacks of using hose segments such asthose caused by high temperatures are effectively removed as well.

[0144] While a rigid manifold body having a preformed fluid circuit hasbeen described in the exemplary embodiments described herein, it iscontemplated that such manifold body could also be a hollow or apartially hollow shell incorporating flexible or rigid conduitsinternally between the various ports.

[0145] Alternative Integrated Pump and Manifold Assembly

[0146] In certain scenarios, it may be advantageous to omit the hoseconnections between the pump and manifold block and connect the pumpdirectly to the manifold block. Such an arrangement reduces and hoselength requirements as well as pressure drops occurring across lengthsof hose thus facilitating higher pressure fluid transfers. As the timeof fluid exchange may be increased by moving the fluid more swiftlybetween the fluid reservoir and the fluid servicing apparatus, theoverall number of fluid exchange procedures per day may be increased.Assembly time and leakage due to the incorporation of flexible hosefluid couplings may also be reduced. Such integrated manifold and pumpblock assembly also simplifies maintenance and installation procedures.

[0147] Referring now to FIGS. 17-24 and 31, wherein like components arelike numbered, there is illustrated an alternative integrated manifoldand pump assembly, generally designated 426, for use in conjunction witha fluid exchanging apparatus 20, 720 such as those illustrated in FIGS.1 and 32. Such integrated manifold and pump assembly houses a fluidcircuit, such as the exemplary fluid circuit 430 illustrated in FIG. 25,formed in a rectangular manifold body 431 having a top side 433, anopposing bottom side 435, a rear side 437, a front side 443, a right end445, as viewed in FIGS. 20 and 22, and a left end 447, as viewed inFIGS. 20 and 21. The body sides and ends have generally planar surfacescooperating to form a rectangular block measuring about 190 mm (7.5inches) wide by 76 mm wide (3 inches) by 76 mm (3 inches) high anddefining a number of manifold ports for connecting to various conduitsand other hydraulic control components. Threaded mounting holes 489(FIG. 20) are provided in the front side 443 for fastening the manifoldbody to the housing of the fluid servicing apparatus 20. In thisexemplary embodiment, there are four primary conduit ports, an auxiliarypower steering fluid drain port, recessed vacuum and pressure side pumpports, and a number of flow control component ports as will be describedin further detail below.

[0148] With particular reference to FIG. 24, an exhaust port 432, areturn port 434, a drain port 436, and a fresh fluid supply port 438open outwardly on the rear side 437 of the manifold body 431. While eachof these ports are shown on the same side of the manifold body 431 inFIGS. 17 and 24, it will be appreciated that the ports may be placed atother suitable locations on the manifold body. For instance, these samemanifold ports are shown on different sides of the manifold body 431 inFIG. 25 for ease of description and clarity and may also providesuitable port locations and is not meant to be limiting in any manner.Other suitable locations will occur to one of ordinary skill in the art.Each manifold port is threaded for coupling with one end of a respectiveconduit, hose, or other suitable tubing or piping, which are in turnconnected to a desired source or destination. For ease of assembly, itis preferable to thread one portion of each hose coupling, generallydesignated 448, into the respective threaded port opening. The threadedcoupling component is constructed to allow the assembler to merely pressthe free end of the selected conduit onto the complementary couplingcomponent threaded into the port. Suitable couplings of this type areavailable from Parker Hannifin under the TrueSeal trade name.

[0149] More specifically, with reference to FIGS. 17, 24 and 25 a usedfluid conduit 439 connects between the drain port 436 and a used fluidcollection tank 440 to carry fluid therebetween. Similarly, the freshfluid supply port 438 connects via a new fluid supply conduit 441 to anew fluid tank 442. Used and new fluid conduits 439 and 441 areconstructed the same as conduits 39 and 41, respectively. Such usedfluid collection tank 440 is constructed to hold a sufficient amount ofused fluid to accommodate at least complete drain procedure andpreferably more. The new fluid tank 442 is typically constructed to holda sufficient volume of fresh fluid to accommodate a single fillprocedure and preferably has a greater capacity as well. This freshfluid source 442 may be filled through a fill hole (not shown). As it ispreferred that the servicing apparatus maintain a portable capability,the used and new fluid tanks are preferably mounted inside the cabinet22 (FIG. 1) which is sized to accommodate the preferred tank capacities.It has been found that a 24 quart capacity for both the new and usedfluid tanks accommodates most servicing procedures.

[0150] Referring now to FIGS. 17-18, 24 and 31, the manifold body 431includes an extended section 423 including a circular cavity 427 forhousing a vane pump 424. Within the cavity is a collar 428 having acircular outer diameter abutting the inner diameter of the cavity and aslightly distended inner diameter forming an eccentric inner surface.The vane pump includes main pump body 446 or rotor with movable vanes429 that may slide in and out from the main pump body in a radialdirection as the pump turns to abut the inner eccentric diameter of thecollar. The main pump body 446 includes a central keyhole 449 to receivea complementary key-shaped drive shaft 451 of a relatively high speed,reversible motor 444. Bored into the inner wall 453 of the cavity is thesuction port 450 and vacuum port 452 leading to the rest of the fluidcircuit 430 (FIGS. 25 and 31). As the pump is reversible, however, thesuction and pressure ports are reversible. When the drive shaft 451 ofthe motor 444 is engaged with the pump body 446 and activated, fluid maybe moved through the cavity 427 between the pressure and suction portsand forced through the remainder of the fluid circuit 430.

[0151] The left hand end 447 of the manifold 431 includes threadedfastener holes 455 for receiving complementary threaded fasteners 462for bolting the motor 444 directly to the manifold body 431. The 12 VDcmotor includes positive and negative terminals 479 for connection to thevehicle battery or other power source via a conventional wiring harness.It will be appreciated that such direct manifold body-pump-motorassembly removes the need for suction and pressure side conduits andlessens the pressure drop through the fluid circuit 430.

[0152] With continued reference to FIGS. 3, 12, 17, 24 and 25, furtherconvenience is provided by a set of servicing hoses, 44 and 46respectively for connecting between the return port 434 and the exhaustport 432 of the servicing apparatus 20 and the influent line andeffluent line of the serviceable component such as an automatictransmission as is well known to one of ordinary skill. The use ofconventional adapters is also contemplated if necessary. Such connectionplaces the transmission in fluid communication with the servicingapparatus 20 as will be discussed below.

[0153] Referring now to FIGS. 25-29, added to the fluid circuit 430 area number of pathways formed in the manifold body 431 as well as a numberof flow control and filtering components for routing fluid entering andexiting the manifold between the various fluid ports 432, 434, 436, 438,450 and 452. In this exemplary embodiment, there are four primarypathways (FIGS. 26-29). There is also one auxiliary pathway (FIG. 30)for drain power steering fluid as will be described below. The primarypathways for exchanging automatic transmission fluid include a drainpath for directing fluid flow as indicated by directional arrows 458(FIGS. 25 and 26), a supply path for directing fluid flow as indicatedby directional arrows 461 (FIGS. 25 and 27), a recirculation path fordirecting fluid flow as indicated by directional arrows 459 (FIGS. 25and 28), and a dump path for directing fluid flow as indicated bydirectional arrows 463 (FIGS. 25 and 29).

[0154] It will be appreciated that the manifold body 431 forms a threedimensional fluid circuit and that FIGS. 25-29 are represented in atwo-dimensional layout for ease of description and are not meant to belimiting in any manner. The lines in FIGS. 25-29 represent conduitsthrough the manifold body between ports or flow control components. Forinstance, the fluid ports in FIG. 17 are shown on one side of themanifold body 431 while the same ports are shown on multiple sides ofthe manifold body in FIG. 25. In addition, in FIG. 25, the manifold body431 is not depicted as a rectangular block as in FIG. 17. Theseillustrations are merely to facilitate description of the preferredembodiment. Other suitable port locations and pathways may occur to oneof ordinary skill and still fall within the scope of the presentinvention.

[0155] With continued reference to FIGS. 25-29, each pathway 458, 459,461, and 463 is generally tubular in transverse cross section and madeup of adjacent passage segments bored into the manifold body 431 whichare configured with straight runs meeting at right angles and compactedto minimize the size of the manifold body and further reduce hose lengthrequirements between components coupled to the manifold body and overallhose length requirements of the servicing apparatus. It will beappreciated that the integration of the pump body 446 into the manifoldbody 431 and direct connection of the motor 444 removes the requirementfor any hose connections other than the conduits between the manifoldbody 431 and the new and used fluid tanks and the transmission ports.Some of these right angle segments project into or out of the plane ofthe paper and may not be shown in FIGS. 25-29. It will also beappreciated, when considered from end to end, portions of each pathwaymay extend outside the manifold body and include couplings or connectorsof flexible or rigid material connected to one or more manifold ports.

[0156] With particular reference to FIGS. 25 and 26, during a drainprocedure as will be discussed below, fluid is normally directed in thedirection of arrow 458 through the drain path from the return port 434to the used fluid drain port 436 which may be connected to the usedfluid collection tank 440 via conduit 439. Such passage 458 is formed byan entry bore extending into the manifold body 431, viewed into thepaper in FIG. 18, from the return port 434 to enter a short pre-filtersegment 464 which turns downwardly at a right angle from the entry bore,toward an aperture (not shown) in the bottom side 435 of the bodyaligned with a fluid entrance into an in-line filter 460 to direct fluidinto the filter. In-line filters 460 and 488 are connected to themanifold body 431 in an identical manner as in-line filters 60 and 88(FIGS. 3 and 12) of the previous embodiment and provide the same fluidpath therethrough.

[0157] After exiting the manifold body 431 through the bottom apertureto enter the in-line filter 460, the drain path 458 then reenters themanifold body through the hollow nipple and projects upwardly into thebody into a pre-drain valve segment 469. About the midpoint of the body431, the pre-drain valve segment terminates at an inlet of atwo-position drain/bypass solenoid valve 470 which may be screwed into athreaded valve port 465 on the top side 433 of the manifold body 431 toposition the dual outlet valve 470 in line with both the drain path 458and recirculation path 459 of the fluid circuit 430. Such valve 470includes a drain position, indicated by directional arrow 466, whichdirects fluid entering the inlet of the solenoid 470 out of a drainoutlet of the solenoid 470 and through the remainder of the drain path458 (FIGS. 25 and 26) and a normally open bypass position, indicated bydirectional arrow 468, which directs fluid entering the inlet of thevalve 470 out of an alternate outlet and through a recirculation path480 (FIGS. 25 and 28). Valves 470 and 484 are identical to the valves 70and 84 (FIG. 6) in the previous embodiment

[0158] With continued reference to FIG. 26, the drain path 458 turns ata right angle from the longitudinal centerline of the solenoid 470 intoa post-solenoid segment 472 forming the stem of a T-shaped intersection474. Then the path is bifurcated to, in one branch, enter into a usedfluid connection branch 475 of the T-shaped intersection leading to thedrain port 436 which may be connected to the used fluid collection tank440 via conduit 439. Fluid entering the return port 434 from theserviceable component is thus normally directed along this drain path458 if the drain/bypass solenoid 470 is energized to the drain position466 for collection in the used fluid tank 440.

[0159] Referring now to FIGS. 25 and 28, when the drain/bypass valve 470is energized to the bypass position as indicated by directional arrow468, the recirculation path 459 is opened and the drain path 458 isblocked. The recirculation path 459 shares the same plumbing with thedrain path 458 up to the drain/bypass solenoid 470 including the returnport 434, pre-filter segment 464, drain/recirculation filter 460, andpre-valve segment 469. Continuing through the drain/bypass solenoidvalve 470, when energized to the bypass position 468, the recirculationpassage 459 projects at a right angle to the longitudinal centerline ofthe solenoid to form an L-shaped recirculation loop 480 leading to theexhaust port 432 which may be connected to the transmission inlet viaconduit 46 (FIGS. 1, 3 and 6). Fluid entering the recirculation pathfrom the return port 434 is directed through the solenoid 470 set in thebypass position 468 to exhaust port 432. Such recirculation pathnormally serves to circulate fluid in the direction indicated by arrows459 between the serviceable component and the servicing apparatus andthrough the filter 460 while bypassing the pump 424, used fluid tank440, and new fluid tank 442.

[0160] With continued reference to FIG. 25, and with particularreference to FIG. 27, the fresh fluid supply passage 461 is formed by anentry bore extending into the manifold body 431 from the new fluidsupply port 438 to then turn at a right angle forming an L-shapedpre-supply valve segment 482. The segments discussed herein arepreferably bored into the manifold body during manufacture. Such segmentterminates at a two-position dump/supply solenoid valve 484 which isalso screwed into a threaded port 485 on the top side 433 of themanifold body 431 to position the valve 484 in line with the new fluidsupply passage 461 (FIG. 27) and the dump passage 463 (FIG. 29) in thefluid circuit 430. Such valve 484 includes a normally open supplyposition, indicated by directional arrow 481, which receives fluidwithdrawn from the new fluid supply tank 442 and directs it through theremainder of the supply path 461 (FIG. 27). The supply/dump valve 484also includes a dump position, indicated by directional arrow 483, whichreceives fluid being dumped from the used fluid tank 440 and directssuch fluid on through the remaining portion of the new fluid supplypassage as well (FIG. 29).

[0161] Continuing with the new fluid passage 461, a pre-suction portsegment 486 projects at a right angle to the longitudinal centerline ofthe solenoid 484 and further includes a second right angle turn leadingto the suction port 450 (FIGS. 25 and 27). The suction port 454 opensdirectly into the pump cavity 427 and a pressure port 456 opens directlyinto the pump cavity as well at an offset position from the suction portto position the pump 424 in line with the supply path 461 (FIG. 27) andalso the dump path 463 (FIG. 29) depending on the valve 484 position.Reentering the manifold body 431 through the pressure port, the newfluid supply passage 461 projects downwardly through a pre-supply filtersegment 487 to lead to an aperture (not shown) on the bottom side 435 ofthe manifold body 431 aligned with an entry hole in a supply filter 488.The supply filter 488 is also connected to the manifold body via ahollow, threaded nipple (not shown) on the under side 435 (FIG. 24)similar to the drain filter 88 connection as for the embodimentillustrated in FIG. 12. Exiting the filter 488 through the hollownipple, the new fluid supply path 461 projects upwardly into themanifold body 431 through an auxiliary proportional solenoid 492 andthen turns outwardly toward the back side 437 of the manifold body in anL-shaped segment 494 leading to the exhaust port 432 which may beconnected to the transmission inlet or collection tank via servicinghose 46 (FIG. 3). The final segment 494 of the new fluid supply path 461leading to the exhaust port 432 is common with the last segment of therecirculation path 459.

[0162] The proportional solenoid 492 is optional for providingadditional flow control capabilities, if desired but is not a necessarycomponent of the present invention. Description of this valve and itsoperation will be described below. In its place or in conjunctiontherewith, a check valve may be incorporated at this point in the supplyfluid circuit 461 to prevent fluid from backflowing or otherwiseentering the outlet of the supply filter 488 from the recirculationpath. This feature may also serve to keep the pump 424 primed in use.However, it is preferable to select a suitable pump 424 having anintegrated check valve for incorporation into the servicing apparatus 20so that the external check valve can be omitted altogether. The supplypathway 461 normally serves to conduct fluid from the fresh fluid supply442 connected to the new fluid port 438 and direct the fluid to theexhaust port 432 and to the upstream line of the serviceable componentvia servicing hose 46 to supply fresh fluid thereto. Alternatively, suchpassage 461 can be used to drain the new fluid tank 442 when theservicing hose 46 is coupled to a collection tank.

[0163] Turning now to FIGS. 25 and 29, the fluid circuit 430 alsoincludes the used fluid dump pathway 463 for transporting fluid betweenthe drain port 436 and the exhaust port 432 for draining fluid from theused fluid tank 440 using the common pump 424. With continued referenceto FIG. 29, the dump path 463 begins with at the drain port 436 which isnormally coupled to the used fluid collection tank 440 via the usedfluid conduit 439. The dump path 463 is then formed with a boreprojecting inwardly from the drain port 436 along a straight segment toform the first branch 475 of the T-intersection 474. The path 463bifurcates at intersection 474 to flow through to a straight pre-valvesegment 491 to one inlet of the dual inlet dump/supply solenoid valve484 which controls the flow on to the outlet bore 486 (pre-suction portsegment) leading to the suction port 450 when the valve is energized tothe dump position 483. The remaining portion of the dump path is commonto the new fluid supply path 493 as it exits the solenoid 484 ultimatelyleading to the exhaust port 432 including passage through the outletbore 486 through the suction port 450 to the pump cavity 427. The fluidis then directed through the pressure port 452 on through filter 488,proportional valve 492 to exhaust port 432 through segment 494. Suchpath 463 normally serves to direct fluid withdrawn from the used fluidcollection tank 440 using the common pump 424 to direct used fluidthrough the exhaust port 432. Instead of connecting the service hose 46to the transmission, however, the free end of the service hose istypically placed in a waste fluid receptacle (not shown) for futurestorage so that the used fluid tank 440 may be drained.

[0164] With continued reference to FIGS. 3 and 25-29, fluid typicallyenters the return port 434 from conduit 44 connected to the downstreamport of the transmission and exits the exhaust port 432 to be directedthrough hose 46 to the upstream port of the transmission. Fluid isgenerally circulated through the fluid circuit 430 by the single,reversible pump 424 interposed in the supply and dump pathways 461 and463, respectively, to complete these pathways. Fluid may also becirculated by a pump associated with the serviceable component throughthe drain and recirculation paths 458 and 459, respectively. Directionof the fluid through the fluid circuit 430 is normally determined by therespective positions of the single inlet, dual outlet, drain/bypassvalve 470 and dual inlet, single outlet, dump/supply valve 484. Thedrain/bypass valve 470 operates to direct fluid entering the return port434 through the drain or bypass passages 458 (FIG. 26) and 459 (FIG. 28)respectively with one side of the valve 470 in fluid communication withthe return port 434 and the second side in fluid communication with thedrain port 436 and exhaust port 432. When solenoid 470 enters into thedrain position 466, the bypass passage 459 is blocked off and thepassage between the return port 434 and the drain port 436 is open andfluid may flow in the direction of arrows 458 (FIG. 26). On the otherhand, when the valve 470 is energized to the bypass position 468, thedrain passage 458 is blocked off and the passage between the return port434 and the exhaust port 432 is open establishing a bypass loop 459wherein fluid may circulate in the direction of the arrows 459 andwherein fluid does not circulate through the pump 424 (FIG. 28).

[0165] Referring to FIGS. 3, 25, 27 and 29, connected in fluidcommunication with the supply and dump paths 461 and 463, respectively,is the dump/supply valve 484 with the outlet of the valve in fluidcommunication with the exhaust port 432 and the dual inlet in fluidcommunication with the drain port 436 and new fluid supply port 438.When the valve 484 is energized to the supply position 481, the dumppassage 463 is blocked off and the passage 461 between the new fluidsupply port 438 and the exhaust port 432 is open so that fluid maytherebetween (FIG. 27). On the other hand, when the valve 484 isenergized to the dump position 483, the new fluid supply passage 461 isblocked off and the passage between the drain port 436 and the exhaustport 432 is open establishing a passage 463 for dumping fluid into theused fluid tank 440 by withdrawing such fluid with the common pump 424(FIG. 29). Selection of these valve positions 466, 468, 481, and 483 isdirected by the controller 28 (FIG. 6) which is in electricalcommunication with each of the valves 470 and 484 similar to thatillustrated in FIG. 6, and the operator or service technician using theelectrical command system as will now be described. Fluid exchangeoperations (i.e. drain, fill, re-circulate, and exchange) using thefluid servicing apparatus 20 incorporating the alternative manifold body431 is initiated by an operator at the control panel 130 and automatedby the controller 28 in a similar manner as described above. As thepreferred vane pump requires a minimum amount of voltage, a low voltagewarning indicator may be placed on the control panel 130 to indicate thevehicle's battery is insufficient to power the motor.

[0166] Referring now to FIG. 25, in the event of an overpressurecondition in the fluid circuit 430, an overpressure switch 473 will openat a predetermined pressure point and over pressurized fluid will bedirected along conduit 476 and conduit 479 back through valve 484, setin position 481, to be redirected back through suction port 450 untilthe pressure condition is relieved. Pressure switch 408 is threaded intothreaded port 409 on the top surface 433 of the manifold body 431 andoperates in an identical manner to pressure switch 108 in the embodimentin FIG. 6.

[0167] It will be appreciated that higher volumes of flow than otherconventional transmission fluid exchanging machines may be attainedusing the alternative manifold body 431 with direct pump and motorintegration. For instance, speeds of 3 gpm have been attained using thevane pump and a high speed motor. Such flow rate forces new fluid intothe transmission well ahead of the flow rate as put out by today'svehicles which typically falls in the 1.2 to 1.7 gpm range. With suchhigh flow rates, the proportional valve 492 may be unnecessary but maybe used to provide finer flow rate control features if desired.

[0168] Operation of the Proportional Check Valve Solenoid

[0169] With reference to FIGS. 17, 25, 27, and 29, the optionalproportional solenoid valve 492 may be incorporated into the fluidcircuit 430 in the supply path 461 to provide an additional level offluid flow rate control. A preferred valve is available from Hydac soldunder the designation PWS06020-01X. Such valve is threaded into anauxiliary port 471 on the top side of the manifold body 431 to disposethe valve inline with the supply path 461 with an inlet facing thein-line filter 488 side of the supply path and an outlet facing the exitsegment 494 to the exhaust port 432. This valve has two primarypositions including a check valve position 477 and a variable openingposition 478. As with the other valves, the proportional valve is inelectrical communication with the controller 28 via a wire lead andresponsive to commands provided therefrom. As this valve is optional,the proportional valve 492 may be removed altogether and replaced with athreaded tap and plug (not shown).

[0170] With the valve 492 in the check valve position 477, fluid in therecirculation loop 480 is prevented from flowing into in-line filter 488and is directed out the exhaust port 432. Likewise, fluid issuing forthfrom the pressure port 452 and passing through the in-line filter 488 isprevented from entering the recirculation loop 480 or the exhaust port432. Such position may also keep the pump primed as fluid will not backflow into the pump cavity 427.

[0171] With the valve set to the proportional position 478, thecontroller 28 may incrementally adjust the opening through which thefluid flows through the valve and adjust the corresponding flow ratetherethrough. For example, if the pump 424 provides an unacceptable flowrate of fluid to the exhaust port 432, instead of shutting the pumpdown, the opening in the valve 492 may be increased or reducedaccordingly through commands from the controller 28 automatically untilthe desired flow is achieved. The controller 28 may be programmed tocommand adjustments to the valve opening that are proportional to therates of change in the quantities of the new and used fluids as measuredby the sensors and determined by the controller.

[0172] Alternative Power Steering Fluid Removal

[0173] As the preferred vane pump is reversible, this feature may beused to accommodate alternative fluid drainage such as the powersteering fluid from the power steering fluid reservoir 28. Such pathprovides an alternative to the fluid path illustrated in FIG. 5. It willbe appreciated that as the common pump 424 is used to drain the powersteering fluid, pump 222 (FIG. 5) may be omitted from the integratedpower steering and transmission fluid exchange apparatus.

[0174] With reference with FIGS. 17, 25 and 30, an auxiliary fluidcircuit 530 connecting the used fluid collection tank 440 to a powersteering fluid reservoir 28 for draining used power steering fluid withthe common pump 424 in the direction of arrows 567 is illustrated.Referring to FIG. 30, the auxiliary fluid circuit includes the sameplumbing and componentry as the dump fluid circuit 463 described aboveup to the pump cavity ports 450 and 452. Instead of continuing to thefluid exhaust port 432, however, the auxiliary fluid circuit projectsthrough the manifold at a right angle to the pre-filter segment 487through a one-way check valve 532 to turn outwardly at a right angle toterminate in the rear face 437 of the manifold body 431 (FIGS. 17-18) inthe outwardly facing threaded auxiliary port 502. Screwed into such portis a coupling 506 with a conduit nipple 508 for receiving one end of ahollow drain conduit 510. The other end of the drain conduit 510 isplaced within the power steering fluid reservoir 28 near the bottom ofthe reservoir.

[0175] In operation, the operator connects one end of the conduit 510 tothe conduit nipple 508 and the other end is disposed within the powersteering fluid reservoir. The operator may then switch the pump 424 intoreverse mode using a switch on the control panel 130. The power steeringfluid exchange is then initiated via the control panel 130 whichtransmits a signal to the pump 424 to activate. Upon activation of thepump, fluid will be suctioned from the power steering fluid reservoirthrough the power steering fluid removal circuit 530. More specifically,used power steering fluid will be drawn by the pump 424 through theconduit 510 into the manifold body 431 through the auxiliary port 502.Once inside the manifold, the used power steering fluid is drawn by thepump through the one-way check valve 532 and into the pump cavity 427via the pressure port 452 now acting as a suction port. The pump thenforces the power steering fluid into the suction port 450 now acting asa pressure port and into segment 486 through valve 484 set to position483 by the controller 28. Used power steering fluid is forced outthrough the used fluid port 436 and into a used fluid collection tank440 through conduit 439 where it may disposed of after the powersteering fluid exchange is completed. The addition of power steeringfluid to the reservoir 28 is performed in the same manner describedabove regarding FIG. 4.

[0176] In addition to those hydrostatic pressure head sensors previouslydescribed, other sensor configurations may be used to measure the levelof supply and used fluids upon which either the incoming flow rate oroutgoing flow rates of the respective fluids or both may be adjusted,regulated, and/or balanced. One such embodiment employing an alternativesensor configuration will now be described.

[0177] Dielectric Sensor Control System

[0178] As an alternative to using hydrostatic pressure head sensors as ameans for providing fluid level data, a control system incorporating afluid level measuring device based on capacitance principles may be usedto determine the fluid levels within the used and new fluid tanks andtransmit a measurable parameter to the controller for monitoring andbalancing the flow rate of the used and new fluids to and from the fluidexchanging apparatus.

[0179] Referring now to FIGS. 32-34 and 36, wherein like components arelike numbered, in general terms, an alternative fluid servicingapparatus, generally designated 720, includes a control system with acontroller 728 in communication with a sensing unit, generallydesignated 729, having a used fluid sensor 702 to measure the level ofused fluid 704 in a used fluid tank 740 and a new fluid sensor 700 tomeasure the level of fresh fluid 706 in a supply tank 742 usingcapacitance principles throughout the servicing process. The controller728 is further coupled to a fluid flow control device 791 which mayinclude, either alone or in combination, a pump 24, valves 70 and 84,and an integrated manifold assembly 26, 231, 426 (FIGS. 3, 12, 17-24 and31) housing fluid transfer circuits similar to those illustrated inFIGS. 6-11, 13-16, and 25-30 as described above to balance the flow rateof the incoming and outgoing fluids between the used and new fluid tanks740 and 742, respectively, of the fluid changing apparatus 720 and thereservoir of the vehicular subsystem being serviced by transmittingcommand signals from the controller 728 to the various plumbingcomponents 24, 70 and 84 based on the sensor input from the sensing unit729. As above, while the fluid exchange procedures described herein arepreferably fully automated, the servicing procedures are initiatedthrough a control panel 130 (FIGS. 1 and 2) coupled to the controller728.

[0180] With continued reference to FIGS. 32-34, the fluid servicingapparatus 720 incorporates a used fluid collection tank 740 and a freshfluid supply tank 742 mounted side by side on a tray 721 of a portablewheeled cabinet 22 (FIG. 1). In FIG. 32, the outer housing is removed tofacilitate description of the fluid tanks and sensing unit 729. Both theused fluid collection tank and fresh fluid supply tanks are similarlyconstructed of a suitable plastic material molded into a generallyrectangular shape with planar upper and bottom surfaces. A predeterminedamount of used fluid 704 may be collected in the used fluid tank. Theupper surface 725 of the used fluid collection tank includes a drainaperture for receiving a quick lock cap 727 which may be removed tofacilitate placement of a free end of a drain hose into the tank 740 inorder to drain the used fluid collection tank using the drain proceduresdescribed hereinabove. The bottom surface 735 of the tank is continuousas the sensing unit 729 is top mounted as will be described below. Thisconstruction prohibits leaks as may occur with the bottom mountedpressure sensors.

[0181] The upper surface 725 of the used fluid collection tank 740 alsoincludes a fore and aft apertures. The aft aperture 716 (away from thecontrol panel 130 of FIG. 32) provides a sensor opening enabling aninstaller to insert the used fluid sensor 700 into the collection tank.The fore aperture (not shown) provides an opening for the used fluidconduit 739 to be inserted into the used fluid tank. As above, one endof the used fluid conduit is coupled to the manifold (e.g. 26, 231, or426) for issuing used fluid into the collection tank 740 during thedrain process or drawing used fluid out the collection tank during thedump process. For purposes of this description, the upper level of theused fluid 704 is designated 769 (FIGS. 34 and 35) and tank air abovethe surface of the used fluid is designated 799.

[0182] A threaded fill neck 711 projects above the upper surface 713 ofthe new fluid tank 742 to receive a threaded cap 715 (FIG. 33). The capmay be unscrewed from the fill neck and removed enabling an operator topour fresh fluid into the tank to fill it to the desired capacity. Theupper surface of the new fluid tank includes an aft opening 717 forinsertion of the new fluid sensor 700 into the new fluid tank. A foreopening (not shown) is also provided in the upper surface of the newfluid tank for receipt of one end of the new fluid conduit 741 whichincludes an opposing end that is normally coupled to the manifold (e.g.26, 231, 426) to provide a supply of fresh fluid from the supply tank tothe manifold for further distribution to the reservoir being serviced ondemand. The aft and fore openings of the new fluid tank are transverselyaligned with the corresponding aft and fore openings of the used fluidtank 740 in relation to the controller 728. For purposes of thisdescription, the upper level of the new fluid 706 is designated 771(FIG. 34) and tank air above the surface of the new fluid is designated797.

[0183] A common wall 723 divides the tanks 740 and 742. However, thetanks may also be constructed separately. Both tanks, 740 and 742,preferably have at least a 24 quart capacity and are 24 inches high fromtop to bottom. Larger or smaller capacity tanks may be used asnecessary. To further prevent leaks and releasably secure the sensors700 and 702 and conduits 739 and 741 to their respective tanks, rubberescutcheons 732 a, 732 b may be used within the fore and aft holes inthe upper surfaces 713, 725 of each tank 742, 740 providing a snug fitagainst the sensor or conduit.

[0184] With continued reference to FIGS. 32-34, the sensing unit 729 isconveniently secured to a generally rectangular, single piece,tri-sectional, mounting bracket 708 for top mounting the sensors to thetanks 740 and 742. The mounting bracket includes two elevated sensormounts 710 and 712 separated by a central U-shaped well 714 recessedbelow the upper level of the mounts. The mounts project outwardly atright angles from the sidewalls of the well in the same plane and areparallel to the bottom wall of the well. Each mount 710 and 712 has anupper flat surface defining fore and aft holes (not shown) for receiptof the new and used fluid sensors 700 and 702 and used and new fluidtank fluid conduits 739 and 741, respectively. These fore and aft holesin the bracket 708 are to be aligned with the corresponding foreapertures and corresponding fore apertures 716 and 717 in the top ofeach tank 740 and 742 when the mounting bracket and sensing unit 729 isinstalled.

[0185] With continued reference to FIGS. 32 and 34, a voltage reducer705 in communication with the controller 728 via a wiring harness issecured within the well 714. Such voltage reducer is operable to reducethe supply voltage from the vehicle car battery 787 or other powersource before such voltage is supplied to the sensors 700 and 702 aswould be understood by one of ordinary skill in the art.

[0186] During installation, the bottom wall of the well 714 of thebracket 708 is secured across the top surfaces, 725 and 713, of the usedand new fluid tanks, respectively, with four bolts or other suitablefastener. The top mounting system positions the new and used fluidsensors 700 and 702, respectively in a perpendicular alignment with thecorresponding top and bottom surfaces (713 and 737, 725 and 735) of therespective new and used fluid tanks 742 and 740 when installed. The topmounting system prevents leaks as the bottom surface 735 of the usedtank 740 and the bottom surface 737 of new fluid tank 742 arecontinuous. It will also be appreciated that the positions of each setof conduits and sensors may be reversed. For example, the new fluidconduit 741 may be placed in the aft opening in the bracket 708 whilethe new fluid sensor 700 may be inserted through the fore opening in thebracket closer to the controller 728.

[0187] Referring now to FIGS. 33 and 34, the new fluid level sensor 700includes a signal processing head 751 a and an elongated coaxial probe749 a separated by an enlarged rectangular metallic plate 752 a. Morespecifically, the signal processing head contains a control circuitwithin a plastic housing 707 a for measuring the fluid level 771 in thenew fluid tank 742 by sensing changes in the capacitance due to a riseor fall of transmission fluid within the probe and transmitting avoltage signal proportional to the level of the fluid to the controller728 for further processing. In this exemplary embodiment, the controlcircuit may include an oscillator, a frequency to voltage converter, andpreferably includes an analog to digital converter in the housing. Anexemplary oscillator operates at 20 KHz. The analog to digital converterconverts the analog capacitance signal output from the probe in eithervolts, amperes, or ohms, into a digital signal. In this exemplaryembodiment, the frequency to voltage converter converts an analogvoltage signal sensed by the probe 749 a into a digital voltage signalproportional to the upper level 771 of new fluid in the supply tank 742.

[0188] The sensor head 751 a is in electrical communication with thevoltage reducer 705 and receives a supply of voltage at a reduced leveltherefrom. A wire lead 775 a connects the sensor head 751 a with thecontroller 728 for electrical communication therebetween to transmitdigital voltage signals proportional to the level of the new fluid 771within the new fluid tank 742 as sensed by the new fluid sensor probe749 a to the controller 728 for further processing. Such fluid levelreadings may be transmitted on a periodic basis to determine changes inthe new fluid level as it rises or falls. It will be appreciated thatthe period used to obtain fluid level readings may be decreased so that,in effect, the controller 728 may monitor the fluid level on acontinuous basis.

[0189] With continued reference to FIG. 34, the new fluid sensorprocessing head housing 707 a is mounted on the plate 752 a using asuitable fastener. The plate, preferably constructed of steel, issecured to the new fluid sensor mount 710 also using a suitablefastener. A grounding screw may be threaded into a hole in the plate andconnected to a grounding wire for grounding the probe 749 a.

[0190] The probe 749 a comprises an outer metallic element 753 a and aninner metallic element 757 a. The outer element is a hollow tubepreferably constructed from steel and is welded to the underneath of theplate 752 a. In this exemplary embodiment, the inner diameter of theouter element is one inch. The inner element is a cylindrical rod,preferably constructed of aluminum, with an outer diameter of ⅜ of aninch. The top end of the inner element is threaded through a centralhole in the plate 752 and into the housing 707. The elements aremaintained in a coaxially spaced alignment by upper and lower nylonspacers 759 a and 760 a, respectively maintaining a gap 761 a betweenthe elements (FIG. 33) wherein different dielectrics such astransmission fluid or air may enter. The outer tube includes regularlyspaced perforations 755 a allowing fluid to enter and exit the gap 761 abetween the tubes at a relatively rapid rate. In addition, the bottomend 794 a of the probe 749 a includes an opening 795 a between the outerand inner elements 753 a and 757 a enabling fluid to enter throughbottom edge so the sensor can detect very low level fluid amounts. Theouter tube is preferably via the grounding screw connected to the plate752 a.

[0191] When a voltage is applied across the elements 753 a and 757 a, acapacitor is formed. The coaxial probe 749 a provide a capacitor elementwithin the control circuit in the housing 707 a. The column between theelements forms a dielectric which is either air or a fluid such astransmission fluid or a mixture thereof. Using capacitance principals asdescribed below, a voltage signal proportional to the level of fluidbetween the elements and thus the tank height may be determined with thesensor 700.

[0192] The used fluid sensor 702 is constructed in an identical mannerand numbered accordingly with a “b” designation. For example, the usedfluid probe is designated 749 b. The used fluid sensor is mounted to thebracket 708 on the used fluid sensor mount 712.

[0193] Referring now to FIG. 36, the analog to digital converter 773 a,773 b of the new and used fluid sensors 700 and 702, respectively, areconnected to an input/output (I/O) board 779 on a programmable functionboard (PFB) 777 of the controller 728 through their respective leads 775a, 775 b. As the sensor heads 751 a and 751 b are positioned relativelynear the front end of the servicing apparatus near the controller 728,it will be appreciated that the wiring requirements are somewhatreduced. The I/O board is in turn in electrical communication with aprogrammable logic board (PLB) 781 which includes a quantity calculatorcomponent 783 and a comparator 785 also included in the PFB 777. The I/Oboard is further in electrical communication with the control panel 130,the pump 24, bypass/drain valve 70, and the dump/supply valve 84 (FIGS.2, 3, 6 and 21) to receive and transmit command signals therebetween.The I/O board is also in electrical communication with the battery 787and may be connected to any number of auxiliary valves 789, such as theproportional valve 492 described above (FIG. 25).

[0194] The PLB 781 is programmed to determine the quantity of the fluidin each of the tanks based upon digital voltage signals received fromthe sensors 700 and 702, respectively, using the quantity calculator783, and compare either the respective quantities, the relative changein quantities indicative of used and fresh fluid flow rates, or bothusing the comparator 785. For example, the new fluid quantity may becalculated by multiplying the horizontal cross-sectional area of therectangular supply tank by the fluid level height 771. As the tanks arepreferably rectangular, this is a relatively simple calculation. Theused fluid quantity may be calculated in a similar manner.

[0195] Other suitable tank configurations with their respectivegeometries stored in memory such that the quantity of fluid in the tankmay be determined once the fluid level height is known may be usedwithout detracting from the scope and spirit of the invention.Additional parameters such as fluid density may also be stored in thecontroller memory to be used in the quantity calculation if desired. ThePLB 781 may transmit the new and used fluid quantities, as determined bythe quantity calculator 783, to the comparator 785. The comparator isprogrammed to compare the new and used fluid quantities or change in newand used fluid quantities with one another. The comparator may alsocompare changes in fluid quantity in either one of the tanks alone.

[0196] Based on the comparison, the PLB 781 may generate a signal to theI/O board 779 to activate or deactivate the associated plumbing controlcomponent, i.e. the pump 24 or valves 70 and 84, respectively. It willbe appreciated that the PFB 777 may be a printed circuit board includingeach of these components to form an integrated unit or each componentmay be a discrete unit in a modular form.

[0197] Installation of the Top Mounted Sensing Unit

[0198] It will be appreciated that the modularity of the top mountedsensing unit 729 allows for relatively easy installation. Referring toFIGS. 32-34, the operator initially slides the new fluid probe 749 ainto the aft hole of the new fluid sensor mount 710 of the bracket 708.The plate 752 a of the new fluid sensor 700 is secured to the mount 710using a suitable fastener. The used fluid sensor 702 is secured in alike manner to the used fluid mount 712. The new fluid conduit 741 maythen be slid into the fore opening in the mount 710. A new fluid conduitcollar 763 positions the conduit at the proper height by interferingwith the downward travel of the conduit in relation to the mount 710.The used fluid conduit 739 is then slid into the fore opening used fluidmount 712 and positioned with lower surface of the used fluid conduitcollar 765 abutting the top surface of the mount 712. The ends of theprobes 749 a, 749 b and conduits 739, 741 may be aligned with thecorresponding openings in the top of the new and used fluid tanks, 740and 742, respectively. The installer slides the probes and conduitsthrough the escutcheons 732 a, 732 b and into the corresponding tank toposition the bottom wall of the bracket well 714 across the top surfaces713 and 725 of the used and new fluid tanks. The bracket 708 may besecured to the tanks using suitable fasteners. With the bracket secured,the new fluid sensor probe 749 a extends downwardly from the mount 710,through the aft aperture 717 in the top wall 713 of the new fluid tank742 and into the tank. The bottom end 794 a of the probe 749 a ispositioned in close proximity with the bottom wall 737 of the tank. Thebottom end of the supply fluid conduit 741 is also positioned near thebottom of the new fluid tank.

[0199] Likewise, the bottom end 794 b of the used fluid probe 749 b andthe bottom end of the used fluid conduit 739 a are disposed near or onthe bottom wall 735 of the used fluid tank 740. Installation of thesensing unit 729 is complete when the wire lead 775 a, 775 b of eachsensor 700, 702 is connected to the I/O board 779 on the programmablefunction board 777.

[0200] It will be appreciated that by merely unbolting the well 714 fromthe top of the tanks 740, 742, respectively, and disconnecting the wireleads 775 a, 775 b, the sensing unit 729 may be withdrawn from the tankfor maintenance. It should be appreciated that such modular constructionfacilitates and reduces overall installation time as well as reducingmaintenance time if a sensor needs replacement.

[0201] Operation of the Dielectric Sensing Control System

[0202] Referring now to FIGS. 33-35, and using the new fluid sensor 700as an example, it will be appreciated that by applying a voltagedifferential across each of the spaced apart elements 753 a and 757 a ofthe probe 749 a, a capacitor is created. The dielectric throughout thelength of the probe 749 a may be either air, a fluid such astransmission fluid, or a mixture of both. More specifically, it is knownthat the capacitance for a given length of a coaxial capacitor isdetermined by the formula:

C=(2*π*E ₀ *E _(r) *L)/ln(R _(o) /R _(i))

[0203] where R_(o) is the inside radius of the outside cylinder, R_(i)is the outside radius of the inner cylinder, E₀ is the permittivity offree space (i.e. a vacuum), E_(r) is the dielectric constant or relativepermittivity, and L is the length of the coaxial elements. Thecapacitance is measured in farads. E₀ is a physical constant equal to8.85×10⁻¹² farad per meter (F/m). E_(r) is the relative dielectricconstant of the insulator between the coaxial conductors, e.g. thetransmission fluid (or other fluid being exchanged) or air if no fluidis present. Air has an E_(r) of one while fresh transmission fluidtypically has an E_(r) of around 2.0 to 2.2. As the transmission fluidbecomes more contaminated, such as used transmission oil, the relativedielectric constant will generally increase.

[0204] As the capacitance of the probe 749 a changes due to rising orfalling fluid levels in the gap 761 a of the probe 749 a, the frequencyof a voltage differential applied across the probe elements 753 a and757 a will vary correspondingly. By sensing the occurrence of changesbetween the outgoing voltage frequency applied across the probe elements753 a and 757 a by the control circuit in the sensor processing head 751a and the incoming voltage frequency received by the control circuit andthe timing between such frequency changes, the height of the column offluid within the gap 761 a may be measured relative to the length of theprobe which is a known parameter. In this example, the probe length is25 inches while the tank height is 24 inches.

[0205] Relying on these principles, the control circuit in the sensorhead 751 a is integrated with the probe 749 a which acts as a capacitorin the control circuit. Upon application of a relatively low voltage,received from the voltage reducer 705, across the elements 753 a and 757a at a particular frequency with an oscillator, e.g. 20 KHz, the controlcircuit senses changes between the outgoing voltage frequency and theincoming voltage frequency, and measures the time for such changes tooccur, also called the frequency response. Such frequency responsevaries as the capacitance of the circuit varies which occurs as thecolumn of fluid in the gap 761 a rises or falls. If there is no changein frequency occurs, the fluid level is not changing. By measuring thetime it takes for the frequency to change, the location along the lengthof the probe 749 a at which point the dielectric changes from oil to airmay be determined. This point along the probe 449 a equates to the upperlevel 771 of the new fluid 706.

[0206] The change in voltage frequency is then converted into an analogvoltage signal using a conventional frequency to voltage converter inthe control circuit in the sensor head 751 a. Such voltage signal isdependent upon and proportional to the height of the fluid column in thegap 761 a. The analog to digital converter 773 a converts the analogvoltage signal to a digital voltage signal and transmits the digitalvoltage signal to the I/O board 779 via wire lead 775 a. A voltageversus height table may be stored in the controller 728 memory forconvenient lookup by the PLB 781.

[0207] As an example, the voltage-height table may include a 4 voltsetting corresponding to the upper surface 713 (maximum height) of thetank 742 and a 0 volt setting corresponding the bottom surface 737(minimum height) of the tank interior may be set to zero volts. Thus, iftwo volts are transmitted from the analog to digital converter 773 a ofthe new fluid sensor 700 to the I/O board 779 of the controller 728, thefluid level would be determined by the controller to be half way up thedielectric probe 749 a. By pulsing the voltage in the control circuit atperiodic intervals and measuring the incoming frequency changes and timeof frequency response, the level of the new fluid 706 in the probe 749 amay be periodically monitored. The used fluid sensor 702 may be operatedin an identical manner for measuring the level of fluid 769 in the usedfluid tank 740.

[0208] Construction of such a control circuit would be understood by oneof ordinary skill in the art. The sensors 700 and 702 are available fromNorco Industries in Elkhart, Ind. It will be appreciated that whileother more sophisticated fluid level sensors could be used, with theconstruction described herein, the sensors 700 and 702 are relativelyinexpensive compared to their counterparts on the market and provide asignificant improvement in accuracy over the hydrostatic pressuresensors commonly used in the transmission servicing industry. Inaddition, the improved accuracy enables faster pumps to be used such asthe 3.0 gpm pump 424 described above.

[0209] In practice, with reference to FIGS. 32-36, once the sensing unit729 is installed as above, the operation of the fluid servicingapparatus 720 is generally same as the previously described embodiment20 incorporating either manifold 31, 231, or 431 using the control panel130 (FIGS. 1, 2, 6, 7, 17 and 25) except that fluid level height isprovided to the controller 728 via the dielectric sensing units 700 and702.

[0210] As before, the new fluid tank 742 is filled to capacity and theservicing hoses 44 and 46 (FIG. 1) are connected to the transmissionports. The vehicle battery 787 is connected via a wiring harness to thecontroller 728 to supply power to the controller 728 and other fluidcontrol components. i.e. the pump 24 or 424, valves 70, 84 and includingthe sensors 700 and 702 which are in electrical communication with thecontroller 728.

[0211] Assuming the used fluid tank 740 is empty and the new fluid tank742 is full, the desired fluid amount for replacement is selected viathe control panel 130 as described above. The quantity selection istransmitted from the control panel 130 to the I/O board 779 and storedin the PLB 781. An initial fluid level reading of each tank 740 and 742is then taken as follows. The PLB transmits a command to the I/O boardto activate the sensors 700 and 702 through their respective leads 775 aand 775 b. Upon receipt of a command signal from the I/O board, thesensor processing head 751 a of the new fluid sensor 700 sets up avoltage differential between the inner element 757 a and the groundedouter tube 753 a to establish a capacitance in the control circuit ofthe new fluid sensor processing head 751 a. As described above, thecontrol circuit determines the level of fluid in the new fluid tank fromthe frequency response and converts the analog voltage signal from thefrequency to voltage converter to a digital voltage signal. The digitalvoltage signal is transmitted via wire lead 775 a to the I/O board 779for further processing. The initial new fluid quantity is determined bythe PLB 781 based on the digital voltage signal corresponding to the newfluid level height 771 provided by the new fluid level sensor 700. Aninitial reading of the used fluid level 769 is taken by the controller728 in a similar manner using the used fluid level sensor 702. Thecurrent level 771 of the new fluid 706 and the current level of the usedfluid 769 are stored in the controller 728 memory.

[0212] As in the above embodiments, a calculation is performed by theCPU to determine if enough fresh fluid 706 is available for the exchangeand if the used fluid level 769 is sufficiently low to receive thedesired quantity of used fluid. Assuming both conditions are acceptable,the operator initiates the fluid exchange procedure as in the priordescribed embodiments via the control panel 130 (FIGS. 1 and 3).

[0213] In this exemplary embodiment, the controller 728 initiates theincremental automated drain and fill fluid exchange procedure asdescribed above once the operator depresses the start exchange button onthe control panel 130 (FIG. 3). Initially, {fraction (6/10)} of a quartof fluid is drained from the vehicle reservoir. Once {fraction (6/10)}of a quart of fluid is drained from the used fluid tank 740 as sensed bythe used fluid sensor 702, the fill process is initiated by thecontroller 728. The controller then actuates the pump 24 to transfer alike amount to the vehicle reservoir as measured by the new fluid sensor700. This procedure generally continues back and forth until thecontroller 728 detects a fluid quantity equal to the fluid exchangequantity selected by the operator via the control panel 130 has beentransferred out of the new fluid tank 742.

[0214] Throughout the fill and drain processes, the PLB 781 (FIG. 36)receives the digital voltage signals through the I/O board 779 from thesensor head 751 a of the new fluid sensor 700 and the sensor head 751 bof used fluid sensor 702 on a periodic basis. When received by the PLB781, such voltage signals represent the current level of the new andused fluids within their respective tanks 740 and 742 as generated bythe varying capacitance in each sensor due to changes in the level oftransmission fluid in the respective gaps 761 a, 761 b between thecoaxial electrodes at the upper surface of the fluid. From such digitalvoltage signals, the respective fluid quantities of the used fluid tank740 and the new fluid tank 742 are computed by the PLB 781 inconjunction with the quantity calculator 783. A comparison of the fluidquantities is then performed by the comparator 785. Based on thecomparison, a command signal is sent from PLB 781 to the I/O board toactivate or deactivate one the fluid control rate devices 791 such asthe pump 24, valve 70, valve 84, or auxiliary valve 492. By actuatingthe various fluid rate control devices, the incoming flow rate of theused fluid and the outgoing flow rate of the new fluid may besubstantially matched. Alternatively, if desired the flow rate of theused or new fluids may be controlled in isolation or a topping offprocedure may be performed.

[0215] For example, turning now to FIGS. 34 and 35, the used fluidsensor 702 may detect an initial used fluid level as indicated inphantom lines and designated 796. The digital voltage signalcorresponding to this fluid level is transmitted to the I/O board 779which passes through the signal to the PLB 781 for further processing.An initial used fluid quantity is determined by the PLB 781 based on thedigital voltage signal. As the drain process continues and used fluid704 enters the used fluid tank 740 through the used fluid conduit 739and rises within the gap 761 b of the used fluid sensor probe 749 b, andafter a designated period of time, a second digital voltage signal istransmitted to the PLB that corresponds to the higher used fluid leveldesignated 769.

[0216] In a similar manner, the new fluid sensor 700 may detect a supplyfluid level at the initial height shown in phantom lines and designated766 and then at a lower level designated by reference numeral 762 aftera new periodic fluid level measurement is taken by the new fluid sensor700. Each of these sensed levels 766 and 762, wherein the dielectricchanges from oil to air, indicates the current highest level of the newfluid in the new fluid tank 742 at a particular time.

[0217] The change in the used fluid quantity may be determined by thePLB 781 based on the initial used fluid level 796 and the subsequenthigher used fluid level 769. Likewise, the change in new fluid quantitymay be determined by the PLB based on the initial new fluid level 762and the lower new fluid level 771. Based upon the relative fluid heightstaken at periodic intervals, the flow rates of both the new fluid 706and the used fluid 704 may be calculated by the PLB 781 and comparedusing the comparator 785. Depending on the outcome of the comparison,the fluid flow rates may be adjusted by sending a command signal fromthe PLB 781 through the I/O board 779 to the desired flow control device24, 70, 84 as necessary. The mechanics of controlling the flow controldevices is the same as the previously described embodiments.

[0218] As the maximum and minimum fluid heights are known, the system720 can be programmed to terminate the fluid transfer process should thefluid level exceed a predetermined limit or decrease below apredetermined base amount. Separate fill and drain procedures may beinitiated by the operator using the above described methods as well. Ithas been found that the dielectric sensors described herein are capableof maintaining accurate fluid level measurement with only a 1-2% rangeof error. Thus, it will be appreciated that any topping off procedureswill be more precise using the dielectric sensor package.

[0219] As used fluid becomes more contaminated, typically the dielectricconstant will increase, however, it will always be greater than thedielectric constant of air and the upper level of the fluid is easilydetected even if the fluid is severely contaminated. The frequency willchange as the differing capacitance is detected.

[0220] Other fluid level sensors using capacitive principles to measuredielectric changes to sense fluid levels may be used. For example, itwould also be possible to use a more expensive continuous coaxial,internal top mounted, fluid level sensing unit such as that sold underthe designation Leveltrak and is available from Efector, Inc. of ExtonPa. However, the cost of such devices is generally prohibitive and theabove described coaxial sensors, available from Norco Industries inElkhart, Ind., are preferred.

[0221] Other examples of sensors using capacitance principles include asingle coated metallic rod and an exterior mounted metal strip forsensing the changes in capacitance due to fluid level changes. These mayalso be suitable. However, the top mounted, internal, coaxial sensor isthe preferred configuration. As the accuracy of a single coated metallicrod degrades in the presence of sloshing fluids and the exterior mountedsensor is susceptible to exterior vibration (walk-by) and externalinterference with the sensing field, it has been found that the coaxialprobe construction inserted into the tank avoids these drawbacks and isthe preferred manner of sensing the fluid levels in the tanks.

[0222] While the present invention has been described herein in terms ofa number of preferred embodiments for performing fluid servicingprocedures on a vehicle, various changes and improvements may also bemade to the invention without departing from the scope thereof. Forexample, while the embodiments described herein have primarily beendescribed in terms of exchanging transmission and power steering fluids,these are meant to be illustrative examples and not meant to be limitingin any manner. For example, using a suitable adapter or connector, othervehicle subsystems having fluid reservoirs such as engine coolant orengine oil may be serviced. Although a vane pump is the preferredpumping means in the embodiment illustrated in FIG. 17 for itsrelatively high speed and low noise output, other suitable pumping meansincluding, for example, gear pumps and diaphragm pumps may be used aswell.

What is claimed is:
 1. An apparatus for servicing an automobile fluidcontaining subsystem having a fluid reservoir with a subsystem pump andan inlet port and an outlet port, said apparatus comprising: a manifolddefining a first manifold port for coupling to said inlet port, a secondmanifold port for coupling to said outlet port, a fresh fluid manifoldport, a used fluid manifold port, and a fluid transfer circuittherebetween; a first valve having a valve inlet port in communicationwith said second manifold port and a valve outlet port in communicationwith said first manifold port and said used fluid port, said first valvebeing selectively operable to place said second manifold port incommunication with either said first manifold port or said used fluidmanifold port; a fresh fluid source coupled to said fresh fluid manifoldport; a common pump interposed between said fluid manifold ports andsaid first manifold port for pumping a fluid from either of said fluidmanifold ports to said first manifold port; a second valve having avalve outlet port in communication with said common pump and a valveinlet port in communication with said used fluid manifold port and saidfresh fluid manifold port, said second valve being selectively operableto place said used fluid manifold port or said fresh fluid manifold portin communication with said first manifold port; whereby, upon couplingsaid first manifold port to said inlet port and said second manifoldport to said outlet port, said subsystem pump may be activated and saidcommon pump may be selectively operated to direct at least one fluidthrough said fluid transfer circuit as determined by the selectiveoperation of at least one of said valves.
 2. The apparatus as set forthin claim 1 wherein: said first manifold port is a return port; saidsecond manifold port is an exhaust port; and said fluid transfer circuitincludes a drain path for directing fluid entering said return port tosaid used fluid manifold port, a bypass path for directing fluidentering said return port to said exhaust port, a supply path fordirecting fluid entering said fresh fluid manifold port to said exhaustport, and a dump path for directing fluid entering said used fluidmanifold port to said exhaust port.
 3. The apparatus as set forth inclaim 2 wherein: said manifold is constructed to cause said drain andbypass paths to diverge at a point in said fluid transfer circuitdownstream from said return port.
 4. The apparatus as set forth in claim2 wherein: said manifold is constructed to cause said supply and dumppaths to converge at a point in said fluid transfer circuit upstream ofsaid exhaust port.
 5. The apparatus as set forth in claim 3 wherein:said first valve is disposed in said fluid transfer circuit at saidpoint of divergence and is selectively operable between a drain positionand a bypass position.
 6. The apparatus as set forth in claim 4 wherein:said second valve is disposed in said fluid transfer circuit at saidpoint of convergence and is selectively operable between a supplyposition and a dump position.
 7. The apparatus as set forth in claim 2wherein: said paths are formed of adjacent linear segments within saidmanifold.
 8. The apparatus as set forth in claim 1 wherein: saidmanifold includes a suction port downstream of said second valve and apressure port upstream of said first manifold port; and said common pumpincludes a suction side coupled to said suction port via a suction hoseand a pressure side coupled to said pressure port via a pressure hose.9. The apparatus as set forth in claim 1 further including: a used fluidreceptacle coupled to said used fluid manifold port.
 10. The apparatusas set forth in claim 9 wherein: said used fluid receptacle includes aused fluid sensor for providing an indicator proportional to a usedfluid level in said used fluid receptacle; and said fresh fluid sourceincludes a new fluid sensor for providing an indicator proportional to afresh fluid level in said fresh fluid source.
 11. The apparatus as setforth in claim 10 further including: a controller coupled to said usedfluid sensor for receiving a first signal proportional to a level offluid within said used fluid tank, said processor being coupled to saidnew fluid sensor for receiving a second signal proportional to a levelof fluid within said fresh fluid source.
 12. The apparatus as set forthin claim 11 wherein: said controller is coupled to said common pump andsaid valves which are selectively operable based on signals receivedfrom said used and new fluid sensors.
 13. The apparatus as set forth inclaim 1 further including: a fluid transfer segment leading to saidsecond manifold port and including a pressure sensor in communicationwith said fluid transfer segment for sensing fluid pressure in saidsegment.
 14. The apparatus as set forth in claim 1 further including: adrain side filter connected to said manifold and interposed between saidsecond manifold port and said first valve.
 15. The apparatus as setforth in claim 1 further including: a supply side filter connected tosaid manifold and interposed between said pump and said first manifoldport.
 16. The apparatus as set forth in claim 1 further including: afirst filter connected to said manifold and interposed between saidsecond manifold port and said first valve; and a second filter connectedto said manifold and interposed between said pump and said firstmanifold port.
 17. The apparatus as set forth in claim 16 wherein: saidfirst and second filters are connected to said manifold by first andsecond threaded, hollow, nipples.
 18. The apparatus as set forth inclaim 1 further including; a check valve interposed between said pumpand said first manifold port for preventing a backflow of fluid fromentering an outlet of said pump.
 19. The apparatus as set forth in claim1 wherein: said common pump is irreversible.
 20. The apparatus as setforth in claim 1 wherein: said common pump incorporates a check valvefor maintaining pump in a primed condition when in use.
 21. Theapparatus as set forth in claim 1 wherein: wherein said first and secondvalves are 2-position, 3-way solenoid valves.
 22. The apparatus as setforth in claim 11 further including: a pair of battery cables inelectrical communication with said controller, said pump, and saidvalves for connecting to a power source.
 23. The apparatus as set forthin claim 11 wherein: said controller includes a processor and is coupledto a control board for receiving operator commands.
 24. The apparatus asset forth in claim 2 wherein: said first valve is selectively operableto cross over the flow of fluid between the drain path and the supplypath.
 25. The apparatus as set forth in claim 24 wherein: said firstvalve is a 3-position, 4-way solenoid valve including a fluid exchangeposition, a circulation position, and a cross over flow position. 26.The apparatus as set forth in claim 9 further including: wherein saidmanifold, said used fluid receptacle, said fresh fluid source, and saidcommon pump are housed in a wheeled cabinet.
 27. The apparatus as setforth in claim 23 wherein: said control board includes an options menuregion listing a plurality of servicing options available to anoperator, a display region including a counter display and a pluralityof status and informational indicators, and a control region including aplurality of actuator buttons for inputting operator commands to saidcontroller.
 28. The apparatus as set forth in claim 27 wherein: saidcontrol region includes a start button which is selectively operable totransmit a signal to said controller to initiate a fluid exchange mode.29. The apparatus as set forth in claim 27 wherein: said control regionincludes a cycle sensors button which is selectively operable totransmit a signal to said controller to actuate said first and secondvalves back and forth between valve positions.
 30. The apparatus as setforth in claim 27 wherein: said control region includes a quantityselection button which is selectively operable to illuminate one of aplurality of quantity indicators in said status region and transmit aselected quantity signal to said controller.
 31. The apparatus as setforth in claim 27 wherein: said processor is programmed to accumulate atotal quantity of fluid measured by at least one of said used or newfluid sensors and display said total quantity in said counter displayupon actuation of a button in said control region.
 32. The apparatus asset forth in claim 27 wherein: said control region includes a drainbutton which is selectively operable to transmit a signal to saidprocessor to actuate said second valve to a dump position and saidcommon pump to pump fluid from said used fluid receptacle to said secondport.
 33. An apparatus as set forth in claim 27 wherein: said controlregion includes an options button for selectively scrolling through saidoptions menu listing and displaying a selected option in said displaycounter, said selected option being initiated upon selection of a startbutton in said control region.
 34. An apparatus as set forth in claim 27wherein: said display region includes an indicator which illuminates toalert an operator of an incorrect hose coupling condition.
 35. Anapparatus as set forth in claim 1 wherein: said common pump is the solepump in said apparatus.
 36. A method of servicing an automobilesubsystem including a fluid reservoir having an upstream component and adownstream component and a subsystem pump with a servicing apparatushaving a return hose coupled to said downstream component and a supplyhose coupled to said upstream component and including an apparatus pumpand a processor, said method comprising: selecting a fluid quantity tobe exchanged; activating said subsystem pump to pump subsystem fluidinto said servicing apparatus via said return hose; removing anincremental amount of subsystem fluid less than said selected fluidquantity by opening a drain passage; closing said drain passage uponremoving said incremental amount of subsystem fluid; opening a supplypassage; activating said apparatus pump to pump a second fluid throughsaid supply passage into said subsystem via said supply hose; addingsaid incremental amount of said second fluid into said fluid reservoir;deactivating said apparatus pump upon adding said incremental amount ofsaid second fluid into said fluid reservoir; and repeating said removingthrough deactivating steps until a total incremental amount of fluidadded to said subsystem is greater than or equal to said selected fluidquantity.
 37. The method of claim 36 further including: coupling a usedfluid tank with a used fluid sensor to said drain passage for collectingsaid subsystem fluid; and coupling a new fluid supply with a new fluidsensor to said supply passage.
 38. The method of claim 37 furtherincluding: reading said used fluid sensor with said processor todetermine said incremental amount of subsystem fluid.
 39. The method ofclaim 37 further including: reading said new fluid sensor with saidprocessor to determine said incremental amount of said second fluid. 40.The method of claim 37 further including: reading said used fluid sensorwith said processor to determine said incremental amount of subsystemfluid; reading said new fluid sensor with said processor to determinesaid incremental amount of said second fluid; and selectively operatingsaid apparatus pump with said processor based on at least one of saidreading steps.
 41. The method of claim 36 further including: providing acirculation passage in said service apparatus; circulating one of saidsubsystem fluid or said second fluid between said servicing apparatusand said subsystem reservoir through said circulation passage and saidreturn and supply hoses.
 42. The method of claim 36 further including:providing a selectively operable valving component coupled to saidprocessor for opening and closing said drain passage and opening saidsupply passage.
 43. The method of claim 36 further including: coupling aused fluid tank to a drain port of said drain passage; collecting saidincremental amounts of subsystem fluid in said used fluid tank to storea collected fluid; uncoupling said supply hose from said upstreamcomponent; opening a dump passage in communication with said drain port;and actuating said apparatus pump to pump said collected fluid from saidused fluid tank through said dump passage and expelling said collectedfluid out said supply hose.
 44. A fluid exchanging apparatus forservicing automobile subsystems having a fluid reservoir including asubsystem pump and an effluent port and an influent port, said apparatuscomprising: a fluid circuit including a drain path for directing fluidentering a return port to a used fluid port, a bypass path for directingfluid entering said return port to an exhaust port, a supply path fordirecting fluid entering a fresh fluid supply port to said exhaust port,and a dump path for directing fluid entering said used fluid port tosaid exhaust port; a rigid manifold body housing at least a portion ofsaid fluid circuit and including a suction port and a pressure portcommon to said dump and supply paths; a divergence of said drain andbypass paths downstream from said return port; a convergence of saidsupply and dump paths upstream of said used fluid port and said supplyport; a first solenoid valve interposed in said divergence of said drainand bypass paths and selectively operable between at least a drainposition and a bypass position; a second solenoid valve interposed insaid convergence of said supply and dump paths and selectively operablebetween at least a supply position and a dump position; a common pumpcoupled to said suction port and said pressure port and interposed insaid fluid circuit between said convergence and said exhaust port fordirecting fluid entering one of said used fluid or supply ports to saidexhaust port; a used fluid collection tank including a used fluid sensorand including a used fluid conduit for connecting to said drain port; anew fluid supply including a new fluid sensor and a fresh fluid conduitfor connected to said supply port; a control board for receivingoperator commands; and a processor coupled to said control board, saidused and new fluid sensors, said pump and said solenoids whereby, uponconnecting said return port to said effluent port and said exhaust portto said influent port and actuating said subsystem pump, and furtherupon receipt of an operator command from said control board, saidprocessor may selectively operate said common pump and selectivelyposition said solenoids based on readings of said used and new fluidsensors and said operator command to direct fluid through said fluidcircuit and between said apparatus and said subsystem.
 45. An apparatusfor servicing automobile subsystems having a fluid reservoir with aneffluent port and an influent port, said apparatus comprising: a fluidcircuit including a drain path connecting a return port to a used fluidport, a bypass path connecting said return port to an exhaust port, asupply path connecting a fresh fluid supply port to said exhaust port,and a dump path connecting said used fluid port to said exhaust port,said drain and bypass paths having a first common section terminating ina divergence downstream from said return port, and said supply and dumppaths forming a convergence to a second common section upstream of saidexhaust port; a flow diverter means including a first component in saiddivergence for diverting flow between said drain and bypass paths and asecond component in said convergence for diverting flow between saidsupply and dump paths; and pumping means interposed upstream of saidconvergence for pumping fluid from one of said drain or supply ports tosaid exhaust port.
 46. The apparatus set forth in claim 45 furtherincluding; a tank collection means for collecting a first fluid expelledthrough said drain port; and a supply means for storing a second fluidto be withdrawn through said supply port by said pumping means.
 47. Theapparatus as set forth in claim 45 further including; controlling meansincluding a processor coupled to said pumping means and said flowdiverter means for selectively operating said pumping means and saidflow diverter means to direct fluid through said fluid circuit.
 48. Anapparatus for exchanging fluid with a vehicle component having areservoir with an inlet and an outlet, said apparatus comprising: afluid circuit defining a supply path and a dump path having a commonfluid delivery section, said supply path connecting a supply manifoldport to an exhaust port and including fresh fluid delivery section, saiddump path connecting a used fluid manifold port to said exhaust port andincluding a used fluid delivery section, said common fluid deliverysection being formed between a convergence of said fresh and used fluiddelivery sections and said exhaust port and including a suction port anda pressure port; a pump coupled to said suction and pressure ports; avalving component interposed in said convergence and selectivelyoperable to open a passage between either of said fresh and used fluiddelivery sections and said common section.
 49. The apparatus as setforth in claim 48 further including: a used fluid tank coupled to saidused fluid manifold port; and a fresh fluid supply coupled to saidsupply manifold port.
 50. The apparatus as set forth in claim 1 furtherincluding: an auxiliary valve interposed between said manifold and saidsubsystem, said auxiliary valve including a housing with a central boreand an auxiliary return port for coupling to said inlet port or saidoutlet port of said subsystem, an auxiliary exhaust port for coupling tothe other of said inlet port or outlet port of said subsystem, a firstpassthrough port coupled to said second manifold port, and a secondpassthrough port coupled to said first manifold port; and a valve bodyslidably received in said bore and, when in use, selectivelypositionable between a first position placing said auxiliary return portin fluid communication with said second manifold port and said auxiliaryexhaust port in fluid communication with said first manifold port and asecond position placing said auxiliary return port in fluidcommunication with said first manifold port and said auxiliary exhaustport in fluid communication with said first manifold port.